Hi,

I'm trying to stop integration if the numeric procedure takes more than ~2 seconds and set the value to zero. As an example consider

restart;
st:=time():
answer:= evalf( Int(SphericalY(161,5,x,5)*SphericalY(262,5,x,x), x=0..10));
t:= time()-st;

This takes 0.63 seconds on my computer, but I wish to stop it after 0.1 seconds as an example. Is there anyway to access the inside of evalf(Int...)) and kill it after 0.1 seconds?

thanks,

Hi,
     I'm comparing a numerical (asymptotic series solution) to a analytical one in Maple 14, 16 and17 (I have many different machines). I make a substitution S(r) = r^(l+1) R(r) to remove singularities and ask maple to solve for S(r) numerically. Then simply

R(r) = S(r)/ r^(l+1) where S(r) is a numeric procedure
and
diff(R(r), r) = diff(S(r),r)/ r^(l+1) - (l+1) S(r)/ r^(l+2) by the  chain rule, and diff(S(r),r) is another numeric procedure returned by maples dsolve.


Now |
S(r)_numeric agrees with S(r)_analytic,
R(r)_numeric agrees with R(r)_analytic,
diff(S(r),r)_numeric agrees with diff(S(r),r)_analytic
BUT diff(R(r),r)_numeric DOES NTO AGREE WITH  diff(R(r),r)_analytic
 
To me this seems that the formula from the chain rule most be wrong. Does anyone have any ideas? I've attached a .msw file too

Thanks,
Matt
testingDRoutside.mw

Hi,

     Seems like a silly questionm but the Maple help page suggested usign the option 'interpolation=false' for a numeric dsolve since I ran out of memory (I'm solving a huge matrix DE). But that's not an option in the command dsolve, has this been removed as of Maple 16? Or any suggestions on using less memory? I have 16Gb RAM, 

Thanks

Hi,

     I have a set of first order, linear ODE's in matrix form, I was able to solve them with matrixDE for 4 equations (which were uncoupled), but I would like to up this to around 132+ equations if possible. When I tried 9 equations I got

 Error, (in collect/series) integer too large in context    

on my laptop and on my other computer it was very slow and I didn't wait for a solution. 

Should I try a numerical solution ...

Hi, 

     I was wondering why numeric integrals that approach zero converge slowly? Is there a way to arrive at the answer (0) faster? Besides proving it symbolically