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https://asciireactor.com/otho/psdlag-agn.git
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81 lines
1.9 KiB
Perl
Executable File
81 lines
1.9 KiB
Perl
Executable File
#!/usr/bin/env perl
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use feature say;
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use utf8;
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use PDL;
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use PDL::FFT;
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use PDL::IO::Misc;
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my $_2π = 2*3.1415926539;
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# space parameters
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our $xres= 0.1;
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our $xmin = 0;
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our $xmax = 2500;
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our $xbins = ($xmax-$xmin)/$xres + 1;
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say "Using $xbins bins";
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# tophat parameters
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my $μ1=7;
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my $Δ1=5; # full width
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my @tophat_list = ([$μ1,$Δ1],[28,8],[15,11]);
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our $tophat_count = 0;
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foreach my $pars (@tophat_list) {
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$tophat_count++;
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# Capture tophat into piddle
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# Complex Number z(x) = u(x) + iv(x)
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my @tophat=tophat(@$pars[0],@$pars[1]);
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my $u = pdl(@tophat);
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my $v = zeroes($u);
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$x_coords = $u->xlinvals($xmin,$xmax);
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# Output x-domain tophat
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wcols $x_coords,$u,"analyses/tables/tophat${tophat_count}.tab";
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# Transform z(x) to Z(x⁻¹) = U(x⁻¹) + iV(x⁻¹)
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my $U = $u;
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my $V = $v;
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fft($U,$V);
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# Determine frequency coordinates
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my $num_elements = nelem($U);
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say "Found $num_elements elements.";
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if ($num_elements % 2 == 0) {
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# even number of bins
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$f = $U->xlinvals(
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-(${num_elements}/2-1)/${num_elements}/${xres}, 1/2/${xres}
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)->rotate(-(${num_elements}/2 -1));
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}
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else {
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#odd number of bins
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$f = $U->xlinvals(
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-(${num_elements}/2-0.5)/${num_elements}/${xres},
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(${num_elements}/2-0.5)/${num_elements}/${xres}
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)->rotate(-(${num_elements}-1)/2);
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}
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# Calculate x offset
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my $φdiff = atan2($V,$U);
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my $offset = $φdiff/($_2π*$f);
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wcols $f,$offset,"analyses/tables/tophat_fft${tophat_count}.tab";
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}
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sub tophat {
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(my $mean,my $width) = @_;
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my $halfwidth = $width/2;
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my @vals = ();
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for (my $x_coord = $xmin; $x_coord <= $xmax; $x_coord += $xres) {
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push @vals, ($x_coord >= ($mean - $halfwidth) &&
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$x_coord <= ($mean + $halfwidth)) ? 1/$width : 0;
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}
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return @vals;
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} |