Hi Ben-
It helps if you include a small working code example rather than
an out-of-context snippet---something we can run. Some thoughts:
- rcols and wcols are useful reading an writing 2D piddles
- $zmatrix_pre seems to be a perl array object with N x M piddle elements
- PDL is optimized for large data operations
- Reading in complex values one-by-one is going to be very slow when
you have 350x350 elements.
- You should be reading all the values in one operation and create the
PDL from that.
I can't help more since your code doesn't even set $row or $col but
maybe the above thoughts will give you an idea. You can use wcols()
to write out a 2D piddle and rcols() to read it back. Something like
this might be applicable from a pdl2 session:
pdl> $im = sequence(5,5)/25;
pdl> $re = random(5,5);
pdl> use PDL::Complex
pdl> p i
0 +1i
pdl> $c = $re + i * $im;
pdl> p $c
[
[0.971898 +0i 0.754039+0.04i 0.50257+0.08i 0.190826+0.12i
0.613931+0.16i]
[0.132726 +0.2i 0.327291+0.24i 0.251733+0.28i 0.184122+0.32i
0.787163+0.36i]
[0.103273 +0.4i 0.793739+0.44i 0.286722+0.48i 0.71684+0.52i
0.939528+0.56i]
[0.114506 +0.6i 0.750494+0.64i 0.757878+0.68i 0.761478+0.72i
0.827088+0.76i]
[ 0.69723 +0.8i 0.438457+0.84i 0.177937+0.88i 0.321631+0.92i
0.750218+0.96i]
]
I recommend trying out small cases in the pdl2 or perldl shells to see
how things
work. Once you see the patterns it is easier to apply to bigger data in
a program
or script.
Cheers,
Chris
On 7/5/2015 14:57, Benjamin Silva wrote:
Hello,
I recently recoded some of my old scripts to use the PDL libraries
instead of some subroutines I had written myself. These scripts were
for doing matrix inversion and matrix manipulation for medium sized
matrices of complex numbers (~350x350 max matrix size). These matrices
are housed in plain text files, and I have a parser that goes through
and builds a piddle out of the data in the file. My old subroutines
were slow to do the processing, but were extremely fast for reading in
the file and creating the matrix. The new subroutine, using PDL, is
extremely fast to do the processing, but now it is crazy slow for
reading in the file and creating the initial PDL. My method for
creating the PDL is shown below. Can anyone please let me know if
there's a faster way to do this? Almost all of the time savings I've
achieved by going to PDL have been consumed by the slower file parsing
and PDL building. I've run the code through a profiler, and it's
definitely wasting a lot of cycles on the 3rd line in the while loop
where I'm creating the cplx data structure.
open (FILE, "$input_file") or die;
while($inline1=<FILE>){
chomp $inline1;
@data = split(/\s+/, $inline1);
$zmatrix_pre[$row][$column] = cplx($data[0]+$data[1]*i);
}
Thanks for any help!
-Ben
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