fftconvolve seems indeed broken. my $p1 = pdl(1,0,0,0); my $p2 = pdl(1,0,0,0); fftconvolve($p1,$p2); print $p1 . "\n";
results in [1.75 -0.25 -0.25 -0.25] It seems that the result is missing the DC component (as if the fft had supressed the 0-freq value) and a factor 2 is missing somewhere. Hernán > Andreas Michalowski michalowski at ifsw.uni-stuttgart.de A simple example is like this: I convolve two 1D piddles, the first is zero except for one value which is 1. The second one has a gaussian shape. I expect as the result a piddle which contains a gaussian shape converging to zero far away from the center. The resulting piddle shows the expected gaussian shape but is not converging to zero, instead of that to a negative constant value. It seems that the result has a negative offset. If I do the convolution with "convolve" instead of "fftconvolve" the result is exactly what I expect. Does someone has an idea why fftconvolve has this (for me) unexpected and (for me) incorrect behavior? Many thanks! Andreas _______________________________________________ Perldl mailing list [email protected] http://mailman.jach.hawaii.edu/mailman/listinfo/perldl
