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intg — definite integral
[v,err]=intg(a,b,f [,ea [,er])
| a,b | : real numbers |
| f | : external (function or list or string) |
| ea, er | : real numbers |
| ea | : absolute error required on the result. Default value: 0 |
| er | : relative error required on the result. Default value: 1.d-8 |
| err | : estimated absolute error on the result. |
intg(a,b,f) evaluates the definite integral from a to b of f(t)dt. The evaluation hopefully satisfies following claim for accuracy: abs(I-v)<= max(ea,er*abs(I)) where I stands for the exact value of the integral.
f is an external :
If f is function its definition must be as follows y = f(t)
If f is a list the list must be as follows: list(f,x1,x2,...) where f is a function with calling sequence f(t,x1,x2,...).
If f is a string it refers to a the name of a Fortran subroutine (see source code of fintg.f)
deff('[y]=f(x)','y=x*sin(30*x)/sqrt(1-((x/(2*%pi))^2))')
exact=-2.5432596188;
abs(exact-intg(0,2*%pi,f))
// See file routines/default/Ex-intg.f
abs(exact-intg(0,2*%pi,'intgex'))
| << intc | intl >> |