Re: Integration in gnuplot IS possible!

[Daniel J S. <dan...@ie...>]

On 06/16/2011 01:57 PM, Hans-Bernhard Bröker wrote:
> On 16.06.2011 02:35, 3snoW wrote:
>
>> I'm not sure if this qualifies as "Dev", If it doesn't I'm sorry.
>> I've searched the web for ways to integrate in gnuplot and only found people
>> saying it is not possible.
>
> Strange --- particularly since one of our published/enclosed demos,
> bivariat.dem, has been doing just that since 1998!

I gave those formulas a try.  They behave better than 3snoW's formulas 
in the example I used, because of the parameter delta (i.e., h) rather 
than the fixed number of intervals of 3snoW and because of its use of 
Simpson's rule.  The bivariat.dem formula still has the problem of 
recursion/stack depth, in this case:

   recursion depth limit exceeded

An internal integration function is probably the only solution to that. 
  The tricky part would be interpreting the function name, i.e.,

f(x) = cos(x)
h = 0.2
M = 1
plot intgrt(f(x),h,M)

where f(x) is the function, h is the (initial) stepsize, M is the 
integration method.  The first argument, in this case "f(x)", would need 
special treatment in the parser different from other functions.

Dan