rNfft to check output is native-complex

fftw3.pd

@@ -401,7 +401,8 @@ EOF
 sub validateArgumentDimensions_complex
 {
   my ( $rank, $thisfunction, $arg ) = @_;
-  my $is_native = !$arg->type->real;
+  barf "Tried to compute a complex FFT, but non-native-complex argument given"
+    if $arg->type->real;
   my $dims_cmp = $arg->ndims;
   barf <<EOF if $dims_cmp < $rank;
 Tried to compute a $rank-dimensional FFT, but an array has fewer than $rank dimensions.
@@ -415,16 +416,18 @@ sub validateArgumentDimensions_real {
 
   # real FFT. Forward transform takes in real and spits out complex;
   # backward transform does the reverse
-  if ( !$is_native && $arg->dim(0) != 2 ) {
-    my ($verb, $var);
-    if ( !$is_native_output && !$do_inverse_fft && $iarg == 1 ) {
-      ($verb, $var) = qw(produces output);
-    } elsif ( $do_inverse_fft && $iarg == 0 ) {
-      ($verb, $var) = qw(takes input);
+  if (!!$do_inverse_fft == !!($iarg == 0)) { # need complex for this
+    my ($verb, $var, $reason) = ($iarg == 0) ? qw(takes input) : qw(produces output);
+    if ( ($iarg == 1 && $is_native_output && !$is_native) ||
+      ($iarg == 0 && !$is_native)
+    ) {
+      $reason = "\$$var should be native-complex";
+    } elsif (!$is_native && $arg->dim(0) != 2) {
+      $reason = "\$$var->dim(0) == 2 should be true";
     }
-    barf <<EOF if $verb;
-$thisfunction $verb complex $var, so \$$var->dim(0) == 2 should be true,
-but it's not (in @{[$arg->info]}: $arg). This is the (real,imag) dimension. Giving up.
+    barf <<EOF if $reason;
+$thisfunction $verb complex $var, so $reason,
+but it's not (in @{[$arg->info]}: $arg). Giving up.
 EOF
   }
 

t/fftw.t

@@ -621,30 +621,39 @@ my $Nplans = 0;
     ok_should_reuse_plan( ! $@, "real ffts shouldn't work inplace - baseline forward" );
     eval { rfft1( inplace sequence(6) ) };
     ok( $@, "real ffts shouldn't work inplace - forward" );
+    eval { rNfft1( sequence(6) ) };
+    ok_should_reuse_plan( ! $@, "real->N ffts shouldn't work inplace - baseline forward" );
+    eval { rNfft1( inplace sequence(6) ) };
+    like $@, qr/in-place real FFTs are not supported/, "real->N ffts shouldn't work inplace - forward";
   }
 
   {
     eval { irfft1( sequence(cdouble,4) ) };
     ok_should_reuse_plan( ! $@, "real ffts shouldn't work inplace - baseline backward" );
-    eval { irfft1( inplace sequence(2,4) ) };
-    ok( $@, "real ffts shouldn't work inplace - backward" );
+    eval { irfft1( inplace sequence(cdouble,4) ) };
+    like $@, qr/in-place real FFTs are not supported/, "real ffts shouldn't work inplace - backward";
   }
 
   {
     eval { rfft1( sequence(7), sequence(2,4) ) };
     ok_should_reuse_plan( ! $@, "real fft dims - baseline");
-
     eval { rfft1( sequence(7), sequence(3,4) ) };
-    ok( $@, "real fft dimensionality 1");
-
+    like $@, qr/produces complex output/, "real fft dimensionality 1";
     eval { rfft1( sequence(7), sequence(1,4) ) };
-    ok( $@, "real fft dimensionality 2");
-
+    like $@, qr/produces complex output/, "real fft dimensionality 2";
     eval { rfft1( sequence(7), sequence(2,5) ) };
-    ok( $@, "real fft dimensionality 3");
-
+    like $@, qr/mismatched first dimension/, "real fft dimensionality 3";
     eval { rfft1( sequence(7), sequence(2,3) ) };
-    ok( $@, "real fft dimensionality 4");
+    like $@, qr/mismatched first dimension/, "real fft dimensionality 4";
+
+    eval { rNfft1( sequence(7), sequence(4) ) };
+    like $@, qr/produces complex output/, "real->N fft type";
+    eval { rNfft1( sequence(7), sequence(cdouble,4) ) };
+    ok_should_reuse_plan( ! $@, "real fft dims - baseline");
+    eval { rNfft1( sequence(7), sequence(cdouble,5) ) };
+    like $@, qr/mismatched first dimension/, "real->N fft dimensionality 1";
+    eval { rNfft1( sequence(7), sequence(cdouble,3) ) };
+    like $@, qr/mismatched first dimension/, "real->N fft dimensionality 2";
   }
 
   {