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From: Greg Heath on 5 Aug 2010 17:51
On Aug 5, 5:07 am, us <u...(a)neurol.unizh.ch> wrote:
> On Aug 5, 9:04 am, "Paul " <unicybs...(a)gmail.com> wrote:
>
>
>
>
>
> > Walter Roberson <rober...(a)hushmail.com> wrote in message <wSo6o.57866$YX3.28...(a)newsfe18.iad>...
> > > Paul wrote:
>
> > > > I want to find value of integral from 0 to 1  exp(t*sin(x))*dx
> > > > with function int I can find integral from 0 to 1  exp(sin(x))*dx
> > > > But if I add independent variable t, than I receive an error from
> > > > function int()
>
> > > > How can I evaluate that integral?
>
> > > My speculation would be that you are not telling int() which variable to
> > > integrate over.
>
> > > Show us how you are calling int() and any critical code leading up to that.
>
> > syms x t;
> > int(exp(-t*sin(x)),x,0,1)
>
> well...
> these work (r2010a)...
> which error(s) do you receive(?)...
>
>      syms x t;
>      int(exp(-t*sin(x)),x,0,1)
> %    Warning: Explicit integral could not be found.
> %    ans = int(1/exp(t*sin(x)), x = 0..1)
>
>      int(exp(-t*sin(x)),t,0,1)
> %    ans = -(1/exp(sin(x)) - 1)/sin(x)
>
> us-

It doesn't even work for the integral representation
of a zeroth order Bessel Function with imaginary argument:

>> int(exp(-i*t*sin(x)),x,-pi,pi)
Warning: Explicit integral could not be found.
> In C:\MATLAB6p5p1\toolbox\symbolic\@sym\int.m at line 58

ans =

int(exp(-i*t*sin(x)),x = -pi .. pi)

Hope this helps.

Greg
From: Greg Heath on 5 Aug 2010 22:27
On Aug 5, 5:51 pm, Greg Heath <he...(a)alumni.brown.edu> wrote:
> On Aug 5, 5:07 am, us <u...(a)neurol.unizh.ch> wrote:
>
>
>
>
>
> > On Aug 5, 9:04 am, "Paul " <unicybs...(a)gmail.com> wrote:
>
> > > Walter Roberson <rober...(a)hushmail.com> wrote in message <wSo6o.57866$YX3.28...(a)newsfe18.iad>...
> > > > Paul wrote:
>
> > > > > I want to find value of integral from 0 to 1  exp(t*sin(x))*dx
> > > > > with function int I can find integral from 0 to 1  exp(sin(x))*dx
> > > > > But if I add independent variable t, than I receive an error from
> > > > > function int()
>
> > > > > How can I evaluate that integral?
>
> > > > My speculation would be that you are not telling int() which variable to
> > > > integrate over.
>
> > > > Show us how you are calling int() and any critical code leading up to that.
>
> > > syms x t;
> > > int(exp(-t*sin(x)),x,0,1)
>
> > well...
> > these work (r2010a)...
> > which error(s) do you receive(?)...
>
> >      syms x t;
> >      int(exp(-t*sin(x)),x,0,1)
> > %    Warning: Explicit integral could not be found.
> > %    ans = int(1/exp(t*sin(x)), x = 0..1)
>
> >      int(exp(-t*sin(x)),t,0,1)
> > %    ans = -(1/exp(sin(x)) - 1)/sin(x)
>
> > us-
>
> It doesn't even work for the integral representation
> of a zeroth order Bessel Function with imaginary argument:

Correction:

It doesn't even work for the following integral
representation of a scaled zeroth order Bessel
Function (similar to the OP's problem when t is
imaginary):

> >> int(exp(-i*t*sin(x)),x,-pi,pi)
>
> Warning: Explicit integral could not be found.
>
> > In C:\MATLAB6p5p1\toolbox\symbolic\@sym\int.m at line 58
>
> ans =
>
> int(exp(-i*t*sin(x)),x = -pi .. pi)

Hope this helps.

Greg
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