19.1 Introduction to Integration | ||
19.2 Functions and Variables for Integration | ||
19.3 Introduction to QUADPACK | ||
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Maxima has several routines for handling integration. The integrate
Dime Short Dime Shredded Stretch Shredded Rustic Stretch Stretch Dime Shredded Short Short Rustic Rustic EfUdUvqw function makes use of most of them. There is also the antid
package, which handles an unspecified function (and its derivatives, of course). For numerical uses, there is a set of adaptive integrators from QUADPACK, named quad_qag
, quad_qags
, etc., which are described under the heading QUADPACK
. Hypergeometric functions are being worked on, see specint
for details. Generally speaking, Maxima only handles integrals which are integrable in terms of the "elementary functions" (rational functions, trigonometrics, logs, exponentials, radicals, etc.) and a few extensions (error function, dilogarithm). It does not handle integrals in terms of unknown functions such as g(x)
and h(x)
.
Makes the change of variable given by f(x,y) = 0
in all integrals occurring in expr with integration with respect to x. The new variable is y.
The change of variable can also be written f(x) = g(y)
.
(%i1) assume(a > 0)$ (%i2) 'integrate (%e**sqrt(a*y), y, 0, 4); 4 / [ sqrt(a) sqrt(y) (%o2) I %e dy ] / 0 (%i3) changevar (%, y-z^2/a, z, y); 0 / [ abs(z) 2 I z %e dz ] / - 2 sqrt(a) (%o3) - ---------------------------- a
An expression containing a noun form, such as the instances of 'integrate
above, may be evaluated by ev
with the nouns
flag. For example, the expression returned by changevar
above may be evaluated by ev (%o3, nouns)
.
changevar
may also be used to changes in the indices of a sum or product. However, it must be realized that when a change is made in a sum or product, this change must be a shift, i.e., Boutique Boutique Shorts Athletic Reebok Reebok i = j+ ...
, not a higher degree function. E.g.,
(%i4) sum (a[i]*x^(i-2), i, 0, inf); inf ==== \ i - 2 (%o4) > a x / i ==== i = 0 (%i5) changevar (%, i-2-n, n, i); inf ==== \ n (%o5) > a x / n + 2 ==== n = - 2
A double-integral routine which was written in top-level Maxima and then translated and compiled to machine code. Use load ("dblint")
to access this package. It uses the Simpson's rule method in both the x and y directions to calculate
/b /s(x) | | | | f(x,y) dy dx | | /a /r(x)
The function f must be a translated or compiled function of two variables, and rSlim Straight Revival Stretch Rock Jean Scarab wq8OAOW6E and s must each be a translated or compiled function of one variable, while a and b must be floating point numbers. The routine has two global variables which determine the number of divisions of the x and y intervals: dblint_x
and dblint_y
, both of which are initially 10, and can be changed independently to other integer values (there are 2*dblint_x+1
points computed in the x direction, and 2*dblint_y+1
in the y direction). The routine subdivides the X axis and then for each value of X it first computes r(x)
and s(x)
; then the Y axis between r(x)
and s(x)
is subdivided and the integral along the Y axis is performed using Simpson's rule; then the integral along the X axis is done using Simpson's rule with the function values being the Y-integrals. This procedure may be numerically unstable for a great variety of reasons, but is reasonably fast: avoid using it on highly oscillatory functions and functions with singularities (poles or branch points in the region). The Y integrals depend on how far apart r(x)
and s(x)
are, so if the distance s(x) - r(x)
varies rapidly with X, there may be substantial errors arising from truncation with different step-sizes in the various Y integrals. One can increase dblint_x
and dblint_y
in an effort to improve the coverage of the region, at the expense of computation time. The function values are not saved, so if the function is very time-consuming, you will have to wait for re-computation if you change anything (sorry). It is required that the functions f, r, and s be either translated or compiled prior to calling dblint
. This will result in orders of magnitude speed improvement over interpreted code in many cases!
demo (dblint)
executes a demonstration of dblint
applied to an example problem.
Attempts to compute a definite integral. defint
is called by integrate
when limits of integration are specified, i.e., when integrate
is called as integrate (expr, x, a, b)
. Thus from the user's point of view, it is sufficient to call integrate
.
defint
returns a symbolic expression, either the computed integral or the noun form of the integral. See quad_qag
and related functions for numerical approximation of definite integrals.
Default value: Shorts Reebok Reebok Boutique Boutique Athletic true
When erfflag
is false
, prevents risch
from introducing the erf
function in the answer if there were none in the integrand to begin with.
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Computes the inverse Laplace transform of expr with respect to s and parameter t. expr must be a ratio of polynomials whose denominator has only linear and quadratic factors. By using the functions laplace
and ilt
together with the solve
or linsolve
functions the user can solve a single differential or convolution integral equation or a set of them.
(%i1) 'integrate (sinh(a*x)*f(t-x), x, 0, t) + b*f(t) = t**2; t / [ 2 (%o1) I f(t - x) sinh(a x) dx + b f(t) = t ] / 0 (%i2) laplace (%, t, s); a laplace(f(t), t, s) 2 (%o2) b laplace(f(t), t, s) + --------------------- = -- 2 2 3 s - a s (%i3) linsolve ([%], ['laplace(f(t), t, s)]); 2 2 2 s - 2 a (%o3) [laplace(f(t), t, s) = --------------------] 5 2 3 b s + (a - a b) s (%i4) ilt (rhs (first (%)), s, t); Is a b (a b - 1) positive, negative, or zero? pos; sqrt(a b (a b - 1)) t 2 cosh(---------------------) 2 b a t (%o4) - ----------------------------- + ------- 3 2 2 a b - 1 a b - 2 a b + a 2 + ------------------ 3 2 2 a b - 2 a b + a
Categories: Laplace transform
Default value: true
When true
, definite integration tries to find poles in the integrand in the interval of integration. If there are, then the integral is evaluated appropriately as a principal value integral. If intanalysis is false
, this check is not performed and integration is done assuming there are no poles.
See also ldefint
.
Examples:
Maxima can solve the following integrals, when intanalysis
is set to false
:
(%i1) integrate(1/(sqrt(x)+1),x,0,1); 1 / [ 1 (%o1) I ----------- dx ] sqrt(x) + 1 / 0 (%i2) integrate(1/(sqrt(x)+1),x,0,1),intanalysis:false; (%o2) 2 - 2 log(2) (%i3) integrate(cos(a)/sqrt((tan(a))^2 +1),a,-%pi/2,%pi/2); The number 1 isn't in the domain of atanh -- an error. To debug this try: debugmode(true); (%i4) intanalysis:false$ (%i5) integrate(cos(a)/sqrt((tan(a))^2+1),a,-%pi/2,%pi/2); %pi (%o5) --- 2
Attempts to symbolically compute the integral of expr with respect to x. integrate (expr, x)
is an indefinite integral, while integrate (expr, x, a, b)
is a definite integral, with limits of integration a and b. The limits should not contain x, although integrate
does not enforce this restriction. a need not be less than b. If b is equal to a, integrate
returns zero.
See quad_qag
and related functions for numerical approximation of definite integrals. See residue
for computation of residues (complex integration). See antid
for an alternative means of computing indefinite integrals.
The integral (an expression free of integrate
) is returned if integrate
succeeds. Otherwise the return value is the noun form of the integral (the quoted operator 'integrate
) or an expression containing one or more noun forms. The noun form of integrate
is displayed with an integral sign.
In some circumstances it is useful to construct a noun form by hand, by quoting integrate
with a single quote, e.g., 'integrate (expr, x)
. For example, the integral may depend on some parameters which are not yet computed. The noun may be applied to its arguments by ev (i, nouns)
where i is the noun form of interest.
integrate
handles definite integrals separately from indefinite, and employs a range of heuristics to handle each case. Special cases of definite integrals include limits of integration equal to zero or infinity (inf
or minf
), trigonometric functions with limits of integration equal to zero and %pi
or 2 %pi
, rational functions, integrals related to the definitions of the beta
and psi
functions, and some logarithmic and trigonometric integrals. Processing rational functions may include computation of residues. If an applicable special case is not found, an attempt will be made to compute the indefinite integral and evaluate it at the limits of integration. This may include taking a limit as a limit of integration goes to infinity or negative infinity; see also ldefint
.
Special cases of indefinite integrals include trigonometric functions, exponential and logarithmic functions, and rational functions. integrate
may also make use of a short table of elementary integrals.
integrate
may carry out a change of variable if the integrand has the form f(g(x)) * diff(g(x), x)
. integrate
attempts to find a subexpression g(x)
such that the derivative of g(x)
divides the integrand. This search may make use of derivatives defined by the gradef
function. See also changevar
and antid
.
If none of the preceding heuristics find the indefinite integral, the Risch algorithm is executed. The flag risch
may be set as an evflag
, in a call to ev
or on the command line, e.g., ev (integrate (expr, x), risch)
or integrate (expr, x), risch
. If risch
is present, integrate
calls the risch
function without attempting heuristics first. See also risch
.
integrate
works only with functional relations represented explicitly with the f(x)
notation. integrate
does not respect implicit dependencies established by the depends
function.
integrate
may need to know some property of a parameter in the integrand. integrate
will first consult the assume
database, and, if the variable of interest is not there, integrate
will ask the user. Depending on the question, suitable responses are yes;
or no;
, or pos;
, zero;
, or neg;
.
integrate
is not, by default, declared to be linear. See declare
and linear
.
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attempts integration by parts only in a few special cases.
Examples:
(%i1) integrate (sin(x)^3, x); 3 cos (x) (%o1) ------- - cos(x) 3 (%i2) integrate (x/ sqrt (b^2 - x^2), x); 2 2 (%o2) - sqrt(b - x ) (%i3) integrate (cos(x)^2 * exp(x), x, 0, %pi); %pi 3 %e 3 (%o3) ------- - - 5 5 (%i4) integrate (x^2 * exp(-x^2), x, minf, inf); sqrt(%pi) (%o4) --------- 2
assume
and interactive query. (%i1) assume (a > 1)$ (%i2) integrate (x**a/(x+1)**(5/2), x, 0, inf); 2 a + 2 Is ------- an integer? 5 no; Is 2 a - 3 positive, negative, or zero? neg; 3 (%o2) beta(a + 1, - - a) 2
gradef
, and one using the derivation diff(r(x))
of an unspecified function r(x)
. (%i3) gradef (q(x), sin(x**2)); (%o3) q(x) (%i4) diff (log (q (r (x))), x); d 2 (-- (r(x))) sin(r (x)) dx (%o4) ---------------------- q(r(x)) (%i5) integrate (%, x); (%o5) log(q(r(x)))
'integrate
noun form. In this example, Maxima can extract one factor of the denominator of a rational function, but cannot factor the remainder or otherwise find its integral. grind
shows the noun form 'integrate
in the result. See also integrate_use_rootsof
for more on integrals of rational functions. (%i1) expand ((x-4) * (x^3+2*x+1)); 4 3 2 (%o1) x - 4 x + 2 x - 7 x - 4 (%i2) integrate (1/%, x); / 2 [ x + 4 x + 18 I ------------- dx ] 3 log(x - 4) / x + 2 x + 1 (%o2) ---------- - ------------------ 73 73 (%i3) grind (%); log(x-4)/73-('integrate((x^2+4*x+18)/(x^3+2*x+1),x))/73$
f_1
in this example contains the noun form of integrate
. The quote-quote operator Shorts Boutique Reebok Reebok Boutique Athletic ''
causes the integral to be evaluated, and the result becomes the body of f_2
. (%i1) f_1 (a) := integrate (x^3, x, 1, a); 3 (%o1) f_1(a) := integrate(x , x, 1, a) (%i2) ev (f_1 (7), nouns); (%o2) 600 (%i3) /* Note parentheses around integrate(...) here */ f_2 (a) := ''(integrate (x^3, x, 1, a)); 4 a 1 (%o3) f_2(a) := -- - - 4 4 (%i4) f_2 (7); (%o4) 600
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Default value: %c
When a constant of integration is introduced by indefinite integration of an equation, the name of the constant is constructed by concatenating integration_constant
and integration_constant_counter
.
integration_constant
may be assigned any symbol.
Examples:
(%i1) integrate (x^2 = 1, x); 3 x (%o1) -- = x + %c1 3 (%i2) integration_constant : 'k; (%o2) k (%i3) integrate (x^2 = 1, x); 3 x (%o3) -- = x + k2 3
Default value: 0
When a constant of integration is introduced by indefinite integration of an equation, the name of the constant is constructed by concatenating integration_constant
and integration_constant_counter
.
integration_constant_counter
is incremented before constructing the next integration constant.
Examples:
(%i1) integrate (x^2 = 1, x); 3 x (%o1) -- = x + %c1 3 (%i2) integrate (x^2 = 1, x); 3 x (%o2) -- = x + %c2 3 (%i3) integrate (x^2 = 1, x); 3 x (%o3) -- = x + %c3 3 (%i4) reset (integration_constant_counter); (%o4) [integration_constant_counter] (%i5) integrate (x^2 = 1, x); 3 x (%o5) -- = x + %c1 3
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Default value: false
When integrate_use_rootsof
is true
and the denominator of a rational function cannot be factored, integrate
returns the integral in a form which is a sum over the roots (not yet known) of the denominator.
For example, with integrate_use_rootsof
set to false
, integrate
returns an unsolved integral of a rational function in noun form:
(%i1) integrate_use_rootsof: false$ (%i2) integrate (1/(1+x+x^5), x); / 2 [ x - 4 x + 5 I ------------ dx 2 x + 1 ] 3 2 2 5 atan(-------) / x - x + 1 log(x + x + 1) sqrt(3) (%o2) ----------------- - --------------- + --------------- 7 14 7 sqrt(3)
Now we set the flag to be true and the unsolved part of the integral will be expressed as a summation over the roots of the denominator of the rational function:
(%i3) integrate_use_rootsof: true$ (%i4) integrate (1/(1+x+x^5), x); ==== 2 \ (%r4 - 4 %r4 + 5) log(x - %r4) > ------------------------------- / 2 ==== 3 %r4 - 2 %r4 3 2 %r4 in rootsof(%r4 - %r4 + 1, %r4) (%o4) ---------------------------------------------------------- 7 2 x + 1 2 5 atan(-------) log(x + x + 1) sqrt(3) - --------------- + --------------- 14 7 sqrt(3)
Alternatively the user may compute the roots of the denominator separately, and then express the integrand in terms of these roots, e.g., 1/((x - a)*(x - b)*(x - c))
or 1/((x^2 - (a+b)*x + a*b)*(x - c))
if the denominator is a cubic polynomial. Sometimes this will help Maxima obtain a more useful result.
Attempts to compute the definite integral of expr by using limit
to evaluate the indefinite integral of expr with respect to x at the upper limit b and at the lower limit a. If it fails to compute the definite integral, ldefint
returns an expression containing limits as noun forms.
ldefint
is not called from integrate
, so executing ldefint (expr, x, a, b)
may yield a different result than integrate (expr, x, a, b)
. ldefint
always uses the same method to evaluate the definite integral, while integrate
may employ various heuristics and may recognize some special cases.
The calculation makes use of the global variable potentialzeroloc[0]
which must be nonlist
or of the form
[indeterminatej=expressionj, indeterminatek=expressionk, ...]
the former being equivalent to the nonlist expression for all right-hand sides in the latter. The indicated right-hand sides are used as the lower limit of integration. The success of the integrations may depend upon their values and order. potentialzeroloc
is initially set to 0.
Computes the residue in the complex plane of the expression expr when the variable z assumes the value z_0. The residue is the coefficient of (z - z_0)^(-1)
in the Laurent series for expr.
(%i1) residue (s/(s**2+a**2), s, a*%i); 1 (%o1) - 2 (%i2) residue (sin(a*x)/x**4, x, 0); 3 a (%o2) - -- 6
Integrates expr with respect to x using the transcendental case of the Risch algorithm. (The algebraic case of the Risch algorithm has not been implemented.) This currently handles the cases of nested exponentials and logarithms which the main part of integrate
can't do. integrate
will automatically apply risch
if given these cases.
erfflag
, if false
, prevents risch
from introducing the erf
function in the answer if there were none in the integrand to begin with.
(%i1) risch (x^2*erf(x), x); 2 3 2 - x %pi x erf(x) + (sqrt(%pi) x + sqrt(%pi)) %e (%o1) ------------------------------------------------- 3 %pi (%i2) diff(%, x), ratsimp; 2 (%o2) x erf(x)
Equivalent to ldefint
with tlimswitch
set to true
.
QUADPACK is a collection of functions for the numerical computation of one-dimensional definite integrals. It originated from a joint project of R. Piessens (1), E. de Doncker (2), C. Ueberhuber (3), and D. Kahaner (4).
The QUADPACK library included in Maxima is an automatic translation (via the program f2cl
) of the Fortran source code of QUADPACK as it appears in the SLATEC Common Mathematical Library, Version 4.1 (5). The SLATEC library is dated July 1993, but the QUADPACK functions were written some years before. There is another version of QUADPACK at Netlib (6); it is not clear how that version differs from the SLATEC version.
The QUADPACK functions included in Maxima are all automatic, in the sense that these functions attempt to compute a result to a specified accuracy, requiring an unspecified number of function evaluations. Maxima's Lisp translation of QUADPACK also includes some non-automatic functions, but they are not exposed at the Maxima level.
Further information about QUADPACK can be found in the QUADPACK book Pullover Boutique Pullover Old Navy Boutique Sweater Sweater Navy Boutique Old U5nBB1.
quad_qag
Integration of a general function over a finite interval. quad_qag
implements a simple globally adaptive integrator using the strategy of Aind (Piessens, 1973). The caller may choose among 6 pairs of Gauss-Kronrod quadrature formulae for the rule evaluation component. The high-degree rules are suitable for strongly oscillating integrands.
quad_qags
Integration of a general function over a finite interval. quad_qags
implements globally adaptive interval subdivision with extrapolation (de Doncker, 1978) by the Epsilon algorithm (Wynn, 1956).
quad_qagi
Integration of a general function over an infinite or semi-infinite interval. The interval is mapped onto a finite interval and then the same strategy as in quad_qags
is applied.
quad_qawo
Integration of cos(omega x) f(x) or sin(omega x) f(x) over a finite interval, where omega is a constant. The rule evaluation component is based on the modified Clenshaw-Curtis technique. quad_qawo
applies adaptive subdivision with extrapolation, similar to quad_qags
.
quad_qawf
Calculates a Fourier cosine or Fourier sine transform on a semi-infinite interval. The same approach as in quad_qawo
is applied on successive finite intervals, and convergence acceleration by means of the Epsilon algorithm (Wynn, 1956) is applied to the series of the integral contributions.
quad_qaws
Integration of w(x) f(x) over a finite interval [a, b], where w is a function of the form (x - a)^alpha (b - x)^beta v(x) and v(x) is 1 or log(x - a) or log(b - x) or log(x - a) log(b - x), and alpha > -1 and beta > -1.
A globally adaptive subdivision strategy is applied, with modified Clenshaw-Curtis integration on the subintervals which contain a or b.
quad_qawc
Computes the Cauchy principal value of f(x)/(x - c) over a finite interval (a, b) and specified c. The strategy is globally adaptive, and modified Clenshaw-Curtis integration is used on the subranges which contain the point x = c.
quad_qagp
Basically the same as quad_qags
but points of singularity or discontinuity of the integrand must be supplied. This makes it easier for the integrator to produce a good solution.
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Integration of a general function over a finite interval. quad_qag
implements a simple globally adaptive integrator using the strategy of Aind (Piessens, 1973). The caller may choose among 6 pairs of Gauss-Kronrod quadrature formulae for the rule evaluation component. The high-degree rules are suitable for strongly oscillating integrands.
quad_qag
computes the integral
integrate (f(x), x, a, b)
The function to be integrated is f(x), with dependent variable x, and the function is to be integrated between the limits a and b. key is the integrator to be used and should be an integer between 1 and 6, inclusive. The value of key selects the order of the Gauss-Kronrod integration rule. High-order rules are suitable for strongly oscillating integrands.
The integrand may be specified as the name of a Maxima or Lisp function or operator, a Maxima lambda expression, or a general Maxima expression.
The numerical integration is done adaptively by subdividing the integration region into sub-intervals until the desired accuracy is achieved.
The keyword arguments are optional and may be specified in any order. They all take the form key=val
. The keyword arguments are:
epsrel
Desired relative error of approximation. Default is 1d-8.
epsabs
Desired absolute error of approximation. Default is 0.
limit
Size of internal work array. limit is the maximum number of subintervals to use. Default is 200.
quad_qag
returns a list of four elements:
The error code (fourth element of the return value) can have the values:
0
if no problems were encountered;
1
if too many sub-intervals were done;
2
if excessive roundoff error is detected;
3
if extremely bad integrand behavior occurs;
6
if the input is invalid.
Examples:
(%i1) quad_qag (x^(1/2)*log(1/x), x, 0, 1, 3, 'epsrel=5d-8); (%o1) [.4444444444492108, 3.1700968502883E-9, 961, 0] (%i2) integrate (x^(1/2)*log(1/x), x, 0, 1); 4 (%o2) - 9
Integration of a general function over a finite interval. quad_qags
implements globally adaptive interval subdivision with extrapolation (de Doncker, 1978) by the Epsilon algorithm (Wynn, 1956).
quad_qags
computes the integral
integrate (f(x), x, a, b)
The function to be integrated is f(x), with dependent variable x, and the function is to be integrated between the limits a and b.
The integrand may be specified as the name of a Maxima or Lisp function or operator, a Maxima lambda expression, or a general Maxima expression.
The keyword arguments are optional and may be specified in any order. They all take the form key=val
. The keyword arguments are:
epsrel
Desired relative error of approximation. Default is 1d-8.
epsabs
Desired absolute error of approximation. Default is 0.
limit
Size of internal work array. limit is the maximum number of subintervals to use. Default is 200.
quad_qags
returns a list of four elements:
The error code (fourth element of the return value) can have the values:
0
no problems were encountered;
1
too many sub-intervals were done;
2
excessive roundoff error is detected;
3
extremely bad integrand behavior occurs;
4
failed to converge
5
integral is probably divergent or slowly convergent
6
if the input is invalid.
Examples:
(%i1) quad_qags (x^(1/2)*log(1/x), x, 0, 1, 'epsrel=1d-10); (%o1) [.4444444444444448, 1.11022302462516E-15, 315, 0]
Note that quad_qags
is more accurate and efficient than quad_qag
for this integrand.
Integration of a general function over an infinite or semi-infinite interval. The interval is mapped onto a finite interval and then the same strategy as in quad_qags
is applied.
quad_qagi
evaluates one of the following integrals
integrate (f(x), x, a, inf)
integrate (f(x), x, minf, a)
integrate (f(x), x, minf, inf)
using the Quadpack QAGI routine. The function to be integrated is f(x), with dependent variable x, and the function is to be integrated over an infinite range.
The integrand may be specified as the name of a Maxima or Lisp function or operator, a Maxima lambda expression, or a general Maxima expression.
One of the limits of integration must be infinity. If not, then quad_qagi
will just return the noun form.
The keyword arguments are optional and may be specified in any order. They all take the form key=val
. The keyword arguments are:
epsrel
Desired relative error of approximation. Default is 1d-8.
epsabs
Desired absolute error of approximation. Default is 0.
limit
Size of internal work array. limit is the maximum number of subintervals to use. Default is 200.
quad_qagi
returns a list of four elements:
The error code (fourth element of the return value) can have the values:
0
no problems were encountered;
1
too many sub-intervals were done;
2
excessive roundoff error is detected;
3
extremely bad integrand behavior occurs;
4
failed to converge
5
integral is probably divergent or slowly convergent
6
if the input is invalid.
Examples:
(%i1) quad_qagi (x^2*exp(-4*x), x, 0, inf, 'epsrel=1d-8); (%o1) [0.03125, 2.95916102995002E-11, 105, 0] (%i2) integrate (x^2*exp(-4*x), x, 0, inf); 1 (%o2) -- 32
Computes the Cauchy principal value of f(x)/(x - c) over a finite interval. The strategy is globally adaptive, and modified Clenshaw-Curtis integration is used on the subranges which contain the point x = c.
quad_qawc
computes the Cauchy principal value of
integrate (f(x)/(x - c), x, a, b)
using the Quadpack QAWC routine. The function to be integrated is f(x)/(x - c)
, with dependent variable x, and the function is to be integrated over the interval a to b.
The integrand may be specified as the name of a Maxima or Lisp function or operator, a Maxima lambda expression, or a general Maxima expression.
The keyword arguments are optional and may be specified in any order. They all take the form key=val
. The keyword arguments are:
epsrel
Desired relative error of approximation. Default is 1d-8.
epsabs
Desired absolute error of approximation. Default is 0.
limit
Size of internal work array. limit is the maximum number of subintervals to use. Default is 200.
quad_qawc
returns a list of four elements:
The error code (fourth element of the return value) can have the values:
0
no problems were encountered;
1
too many sub-intervals were done;
2
excessive roundoff error is detected;
3
extremely bad integrand behavior occurs;
6
if the input is invalid.
Examples:
(%i1) quad_qawc (2^(-5)*((x-1)^2+4^(-5))^(-1), x, 2, 0, 5, 'epsrel=1d-7); (%o1) [- 3.130120337415925, 1.306830140249558E-8, 495, 0] (%i2) integrate (2^(-alpha)*(((x-1)^2 + 4^(-alpha))*(x-2))^(-1), x, 0, 5); Principal Value alpha alpha 9 4 9 4 log(------------- + -------------) alpha alpha 64 4 + 4 64 4 + 4 (%o2) (----------------------------------------- alpha 2 4 + 2 3 alpha 3 alpha ------- ------- 2 alpha/2 2 alpha/2 2 4 atan(4 4 ) 2 4 atan(4 ) alpha - --------------------------- - -------------------------)/2 alpha alpha 2 4 + 2 2 4 + 2 (%i3) ev (%, alpha=5, numer); (%o3) - 3.130120337415917
Calculates a Fourier cosine or Fourier sine transform on a semi-infinite interval using the Quadpack QAWF function. The same approach as in quad_qawo
is applied on successive finite intervals, and convergence acceleration by means of the Epsilon algorithm (Wynn, 1956) is applied to the series of the integral contributions.
quad_qawf
computes the integral
integrate (f(x)*w(x), x, a, inf)
The weight function w is selected by trig:
cos
w(x) = cos (omega x)
sin
w(x) = sin (omega x)
Reebok Shorts Athletic Boutique Reebok Boutique The integrand may be specified as the name of a Maxima or Lisp function or operator, a Maxima lambda expression, or a general Maxima expression.
The keyword arguments are optional and may be specified in any order. They all take the form key=val
. The keyword arguments are:
epsabs
Desired absolute error of approximation. Default is 1d-10.
limit
Size of internal work array. (limit - limlst)/2 is the maximum number of subintervals to use. Default is 200.
maxp1
Maximum number of Chebyshev moments. Must be greater than 0. Default is 100.
limlst
Upper bound on the number of cycles. Must be greater than or equal to 3. Default is 10.
quad_qawf
returns a list of four elements:
The error code (fourth element of the return value) can have the values:
0
no problems were encountered;
1
too many sub-intervals were done;
2
excessive roundoff error is detected;
3
extremely bad integrand behavior occurs;
6
if the input is invalid.
Examples:
(%i1) quad_qawf (exp(-x^2), x, 0, 1, 'cos, 'epsabs=1d-9); (%o1) [.6901942235215714, 2.84846300257552E-11, 215, 0] (%i2) integrate (exp(-x^2)*cos(x), x, 0, inf); - 1/4 %e sqrt(%pi) (%o2) ----------------- 2 (%i3) ev (%, numer); (%o3) .6901942235215714
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Integration of cos (omega x) f(x) or sin (omega x) f(x) over a finite interval, where omega is a constant. The rule evaluation component is based on the modified Clenshaw-Curtis technique. quad_qawo
applies adaptive subdivision with extrapolation, similar to quad_qags
.
quad_qawo
computes the integral using the Quadpack QAWO routine:
integrate (f(x)*w(x), x, a, b)
The weight function w is selected by trig:
cos
w(x) = cos (omega x)
sin
w(x) = sin (omega x)
The integrand may be specified as the name of a Maxima or Lisp function or operator, a Maxima lambda expression, or a general Maxima expression.
The keyword arguments are optional and may be specified in any order. They all take the form key=val
. The keyword arguments are:
epsrel
Desired relative error of approximation. Default is 1d-8.
epsabs
Desired absolute error of approximation. Default is 0.
limit
Size of internal work array. limit/2 is the maximum number of subintervals to use. Default is 200.
maxp1
Maximum number of Chebyshev moments. Must be greater than 0. Default is 100.
limlst
Upper bound on the number of cycles. Must be greater than or equal to 3. Default is 10.
quad_qawo
returns a list of four elements:
The error code (fourth element of the return value) can have the values:
0
no problems were encountered;
1
too many sub-intervals were done;
2
excessive roundoff error is detected;
3
extremely bad integrand behavior occurs;
6
if the input is invalid.
Examples:
(%i1) quad_qawo (x^(-1/2)*exp(-2^(-2)*x), x, 1d-8, 20*2^2, 1, cos); (%o1) [1.376043389877692, 4.72710759424899E-11, 765, 0] (%i2) rectform (integrate (x^(-1/2)*exp(-2^(-alpha)*x) * cos(x), x, 0, inf)); alpha/2 - 1/2 2 alpha sqrt(%pi) 2 sqrt(sqrt(2 + 1) + 1) (%o2) ----------------------------------------------------- 2 alpha sqrt(2 + 1) (%i3) ev (%, alpha=2, numer); (%o3) 1.376043390090716
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Integration of w(x) f(x) over a finite interval, where w(x) is a certain algebraic or logarithmic function. A globally adaptive subdivision strategy is applied, with modified Clenshaw-Curtis integration on the subintervals which contain the endpoints of the interval of integration.
quad_qaws
computes the integral using the Quadpack QAWS routine:
integrate (f(x)*w(x), x, a, b)
The weight function w is selected by wfun:
1
w(x) = (x - a)^alpha (b - x)^beta
2
w(x) = (x - a)^alpha (b - x)^beta log(x - a)
3
w(x) = (x - a)^alpha (b - x)^beta log(b - x)
4
w(x) = (x - a)^alpha (b - x)^beta log(x - a) log(b - x)
The integrand may be specified as the name of a Maxima or Lisp function or operator, a Maxima lambda expression, or a general Maxima expression.
The keyword arguments are optional and may be specified in any order. They all take the form key=val
. The keyword arguments are:
epsrel
Desired relative error of approximation. Default is 1d-8.
epsabs
Desired absolute error of approximation. Default is 0.
limit
Size of internal work array. limitis the maximum number of subintervals to use. Default is 200.
quad_qaws
returns a list of four elements:
The error code (fourth element of the return value) can have the values:
0
no problems were encountered;
1
too many sub-intervals were done;
2
excessive roundoff error is detected;
3
extremely bad integrand behavior occurs;
6
if the input is invalid.
Examples:
(%i1) quad_qaws (1/(x+1+2^(-4)), x, -1, 1, -0.5, -0.5, 1, 'epsabs=1d-9); (%o1) [8.750097361672832, 1.24321522715422E-10, 170, 0] (%i2) integrate ((1-x*x)^(-1/2)/(x+1+2^(-alpha)), x, -1, 1); alpha Is 4 2 - 1 positive, negative, or zero? pos; alpha alpha 2 %pi 2 sqrt(2 2 + 1) (%o2) ------------------------------- alpha 4 2 + 2 (%i3) ev (%, alpha=4, numer); (%o3) 8.750097361672829
Integration of a general function over a finite interval. quad_qagp
implements globally adaptive interval subdivision with extrapolation (de Doncker, 1978) by the Epsilon algorithm (Wynn, 1956).
quad_qagp
computes the integral
integrate (f(x), x, a, b)
The function to be integrated is f(x), with dependent variable x, and the function is to be integrated between the limits a and b.
Casual Market Black Selling White House Dress pw1xFCqThe integrand may be specified as the name of a Maxima or Lisp function or operator, a Maxima lambda expression, or a general Maxima expression.
Boutique Reebok Boutique Athletic Reebok Shorts To help the integrator, the user must supply a list of points where the integrand is singular or discontinous.
The keyword arguments are optional and may be specified in any order. They all take the form key=val
. The keyword arguments are:
epsrel
Desired relative error of approximation. Default is 1d-8.
epsabs
Boutique Boutique Shorts Athletic Reebok Reebok Desired absolute error of approximation. Default is 0.
limit
Size of internal work array. limit is the maximum number of subintervals to use. Default is 200.
quad_qagp
returns a list of four elements:
The error code (fourth element of the return value) can have the values:
0
no problems were encountered;
1
too many sub-intervals were done;
2
excessive roundoff error is detected;
3
extremely bad integrand behavior occurs;
4
failed to converge
5
integral is probably divergent or slowly convergent
6
if the input is invalid.
Examples:
(%i1) quad_qagp(x^3*log(abs((x^2-1)*(x^2-2))),x,0,3,[1,sqrt(2)]); (%o1) [52.74074838347143, 2.6247632689546663e-7, 1029, 0] (%i2) quad_qags(x^3*log(abs((x^2-1)*(x^2-2))), x, 0, 3); (%o2) [52.74074847951494, 4.088443219529836e-7, 1869, 0]
The integrand has singularities at 1
and sqrt(2)
so we supply these points to quad_qagp
. We also note that quad_qagp
is more accurate and more efficient that quad_qags
.
Control error handling for quadpack. The parameter should be one of the following symbols:
current_error
The current error number
control
Controls if messages are printed or not. If it is set to zero or less, messages are suppressed.
max_message
The maximum number of times any message is to be printed.
If value is not given, then the current value of the parameter is returned. If value is given, the value of parameter is set to the given value.
This document was generated by Wolfgang Dautermann on October, 5 2017 using texi2html 1.76.