Reducing Table Run Time
- To: mathgroup at christensen.cybernetics.net
- Subject: [mg1706] Reducing Table Run Time
- From: jt12799 at glibm3.cen.uiuc.edu (Jehan Tsai)
- Date: Wed, 19 Jul 1995 00:13:23 -0400
- Organization: University of Illinois at Urbana
I've got a question about the following bit of code:
k=628300;f=10;
eq1=UnitStep[x+.005]-UnitStep[x-.005];
eq2=Exp[-I k x^2/(2 f)];
g1=Compile[{x},Evaluate[eq1*eq2]];
f1=Table[g1[index],{index,-.2,.2,N}];
Whenever i run this for a value of N necessary to generate a table of
2000+ values, the line to generate table f1 seems to take up a good 80-90% of
the running time, which I understand is due to the evaluation of the function.
My question involves whether or not there is a way to reduce the running
time, or is this something we have to live with? For 2048 samples, I clocked
it at approximately 44s, with most of it taken up by the table. Thanks in
advance.
J.T. Tsai