Hi PDL folks: I just wrote a function that I think should be thread-able,
but I can't think how. Any ideas welcome.
This function is used to up-sample a weather model grid via
linear interpolation. I use the local PP function Dutil::dplinear to do
this. It may be better to use other PDL interpolation functions, but I've
been using this for years and I know just what it does. Here is its
signature:
dplinear (x(n); y(n); in(); [o]out())
It is just a simple interpolation routine which takes $x and $y vectors as
input, along with one value in $x-space to interpolate into $y space.
The tricky bit here is that two sorts of threading are necessary:
1) Interpolating a column of input temperatures via the $x and $y input
to dplinear.
2) Threading over all the lat/lon columns in the input temperature grid
$t. The tricky bit is that the pressure values are different for each
column--this model does not use standard pressure levels, but the pressure
levels at each grid point depend upon the surface pressure.
Any ideas? Please let me know if this is not clear...
Regards,
Doug Hunt
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sub upsampleGrid {
my $lgrid = shift; # low resolution (half) pressure grid: lat x lon x 92
levels
my $hgrid = shift; # high resolution (half) pressure grid: lat x lon x 138
levels
my $t = shift; # temperature grid to upsample: lat x lon x level
my ($nlat, $nlon, $llvl) = $t->dims; # llvl = 92
my $hlvl = ($hgrid->dims)[2]; # 138
my $ht = zeroes($nlat, $nlon, $hlvl); # high resolution output grid
# This could be sped up with threading, I feel sure...
for (my $lati=0;$lati<$nlat;$lati++) {
for (my $loni=0;$loni<$nlon;$loni++) {
my $x = $lgrid->(($lati),($loni),:);
my $y = $t->(($lati),($loni),:);
my $in = $hgrid->(($lati),($loni),:);
$hg(($lati),($loni),:) .= Dutil::dplinear($x, $y, $in);
}
}
return $hg;
}
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[email protected]
Software Engineer
UCAR - COSMIC, Tel. (303) 497-2611
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