Online Algebra Calculator
Many of users do not use powerful Maxima computer algebra system for systematic work, but for ad hoc algebraic calculations – equations, functions, matrixes, etc. only. To do this job, it is not useful to download the whole application from a web site.
Function: quad_qawf (<f(x)>, <x>, <a>, <omega>, <trig>, [<epsabs>, <limit>, <maxp1>, <limlst>])
Function: quad_qawf (<f>, <x>, <a>, <omega>, <trig>, [<epsabs>, <limit>, <maxp1>, <limlst>]) 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)
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:
* an approximation to the integral,
* the estimated absolute error of the approximation,
* the number integrand evaluations,
* an error code.
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(%o1) true (%i2)