Return PDL::Complex types for some arguments.

Changes

@@ -1,3 +1,5 @@
+- PDL::Complex outputs where appropriate - thanks @wlmb
+
 0.11 2021-03-23
 - support PDL 2.027+ "native complex" inputs for fftn and ifftn
 

FFTW3_header_include.pm

@@ -85,7 +85,8 @@ EOF
   eval { no strict 'refs'; $internal_function->( $in, $out, $plan ) };
   barf $@ if $@;
 
-  return $out;
+  ($in->isa('PDL::Complex') && !($do_inverse_fft  && $is_real_fft))
+    ? $out->complex : $out;
 }
 
 sub getOutArgs {
@@ -131,10 +132,9 @@ EOF
 
     my $type = ref $arg;
     $type = 'scalar' unless defined $arg;
-
-    barf <<EOF unless ref $arg && ($type eq 'PDL' or (!$is_real_fft and $type eq 'PDL::Complex'));
-$thisfunction arguments must be of type 'PDL'. Instead I got an arg of
-type '$type'. Giving up.
+    barf <<EOF unless ref $arg && $arg->isa('PDL');
+$thisfunction arguments must be of type 'PDL' (including 'PDL::Complex').
+Instead I got an arg of type '$type'. Giving up.
 EOF
   }
 

t/fftw.t

@@ -66,8 +66,9 @@ sub other2native {
 
   my $x_cplx = cplx $x;
   my $cplx_result = fft1($x_cplx);
-  ok_should_make_plan( all( approx( $cplx_result, $Xref, approx_eps_double) ),
+  ok_should_make_plan( all( approx( $cplx_result, $Xref->cplx, approx_eps_double) ),
                       "Basic 1D complex FFT with PDL::Complex" );
+  isa_ok($cplx_result, 'PDL::Complex', "PDL::Complex return type");
 
   ok_should_make_plan( all( approx( ifft1(fft1($x)), $x, approx_eps_double) ),
                       "Basic 1D complex FFT - inverse(forward) should be the same (normalized)" );
@@ -520,6 +521,16 @@ sub other2native {
   ok_should_make_plan( all( approx( $x7, $x7_back, approx_eps_double) ),
                        "rfft basic test - backward - 7long" );
 
+  # Test real fft's with PDL::Complex arguments
+  my $fx6c=rfft1($x6, zeroes(2,4)->cplx);
+  isa_ok($fx6c, 'PDL::Complex', 'type of real to PDL::Complex forward transform');
+  ok_should_reuse_plan(all( approx($fx6c, $fx6_ref->slice(':,0:3')->cplx, approx_eps_double) ),
+		       'value of real to PDL::Complex forward transform');
+  my $x6c_back=irfft1($fx6c);
+  ok($x6c_back->isa('PDL') && !$x6c_back->isa('PDL::Complex'),
+     'type of PDL::Complex to real backward transform');
+  ok(all( approx($x6c_back, $x6, approx_eps_double) ),
+     'value of PDL::Complex to real backward transform');
 
   # Currently a single plan is made for ALL the thread slices. These tests are
   # meant to exercise cases where this is a bad assumption. I.e. where some