Re: function definition for integration

[Paul Thomas]

Dear All,

quad, in the other product, is one of the "function functions" that can 
feed parameter values to the called function via its own arguments.  I 
do not recall exactly how it goes but it is something like:

[integral err other_stuff] = quad("my_integrand", lower_x , upper_x , 
prec , verbose , P1 , P2 .... PN);

with

function out_val = my_integrand( x , P1 , P2 , .....  PN);

I already ran into this when porting a programme and used a wrapper with 
the parameters fed via global to fix it. Is this somewhere that we 
should go for compatibility?  Note though that the fifth argument is 
already different in octave.

Paul T

Paul Kienzle wrote:

> Or you can include the value of the fixed parameters
> directly in your wrapper function:
>
>     function x=flotest1(a), x=flotest(a,4); end
>
> You can use inline() from octave-forge as a shorthand for this:
>
>     octave:4> quad(inline('flotest(x,4)'),0,1)
>     ans = 4.3333
>
> Paul Kienzle
> address@hidden
>
> On Mar 21, 2004, at 10:53 PM, address@hidden wrote:
>
> > Flo:
> >
> > A simple if inelegant way to pass multivariate functions when only a
> > univariate function is expected is to use global variables and a wrapper
> > function.
> >
> > That is, if your integrand function is
> >
> >     function x = flotest (a, b) x = a^2 + b; endfunction
> >
> > then write a wrapper:
> >
> >     function x = flotest1 (a)
> >       global flotest_b
> >       x = flotest (a, flotest_b);
> >     endfunction
> >
> > define the global variable
> >
> >     octave> global flotest_b
> >     octave> flotest_b = 4;
> >
> > and do the integration:
> >     
> >     octave> quad ("flotest1", 0, 1);
> >     4.3333
> >
> >
> >
> > On Fri, 19 Mar 2004 08:23 pm, address@hidden wrote:
> >
> > > Hi,
> > > Am am using 2.1.40 since 1 week, like it so a far a lot, and would 
> > > like to
> > > integrate a function, defined as with
> > > two variables, whereas I pass on one as number - so as a simple
> > > example s.th. like this, which doesn't do the trick:
> > >
> > > function x=test(a,b)
> > > x= a^2 + b;
> > > endfunction
> > > quad('test(a,4)',0,1)
> > >
> > > So how can I pass on variables not values on to a
> > > defined function ? I
> > > dont try to do anything symbolic. I looked around a good bit in the
> > > documentation, but couldn't figure it out.
> > >
> > > Any hints are appreciated,
> > > Thanks a lot,
> > > Flo
> > >
> > >
> > >
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