fix pow/exp with a constant

TODO

@@ -1,15 +1,11 @@
-- try loading a float image, then 255 * A1 ** 2
-
-GLib-GObject-WARNING **: value "((VipsOperationMath2) 79094592)" of type
-`VipsOperationMath2' is invalid or out of range for property `math2' of type
-`VipsOperationMath2'
-
-
 - test docs
 
   need a set of convenience funcs for C, eg. vips_sin(), vips_more_const() 
   etc. ... could include vips_relational() etc. as well?
 
+  have them all in a separate convenience.h and convenience.c so we can easily
+  compile without them
+
   rewrite im_bandmean() in terms of recomb()? just use [0.33, 0.33, 0.33]
 
   move im_point_bilinear() to deprecated? or convenience?

libvips/arithmetic/arithmetic.c

@@ -363,13 +363,6 @@ vips_arithmetic_build( VipsObject *object )
 		arithmetic->ready, arithmetic ) )
 		return( -1 );
 
-#ifdef DEBUG
-	printf( "vips_arithmetic_build: booltest = %d\n", 
-		arithmetic->booltest );
-	printf( "vips_arithmetic_build: imtest = %p\n", 
-		arithmetic->imtest );
-#endif /*DEBUG*/
-
 	return( 0 );
 }
 
@@ -391,22 +384,6 @@ vips_arithmetic_class_init( VipsArithmeticClass *class )
 		_( "Output image" ),
 		VIPS_ARGUMENT_REQUIRED_OUTPUT, 
 		G_STRUCT_OFFSET( VipsArithmetic, out ) );
-
-	/* Just for testing.
-	 */
-
-	VIPS_ARG_BOOL( class, "booltest", 101, 
-		_( "Bool test" ), 
-		_( "Test optional boolean argument" ),
-		VIPS_ARGUMENT_OPTIONAL_INPUT, 
-		G_STRUCT_OFFSET( VipsArithmetic, booltest ),
-		FALSE );
-
-	VIPS_ARG_IMAGE( class, "imtest", 102, 
-		_( "Image test" ), 
-		_( "Test optional image argument" ),
-		VIPS_ARGUMENT_OPTIONAL_INPUT, 
-		G_STRUCT_OFFSET( VipsArithmetic, imtest ) );
 }
 
 static void

libvips/arithmetic/arithmetic.h

@@ -66,11 +66,6 @@ typedef struct _VipsArithmetic {
 	 */
 	VipsImage *out;
 
-	/* Optional bool argument for testing.
-	 */
-	gboolean booltest;
-	VipsImage *imtest;
-
 	/* Array of input arguments, set these from a subclass.
 	 */
 	VipsImage **in;

libvips/arithmetic/math2.c

@@ -391,7 +391,7 @@ vips_math2_constv( VipsImage *in, VipsImage **out,
 	for( i = 0; i < n; i++ ) 
 		array[i] = c[i];
 
-	result = vips_call_split( "math2_const", ap, in, out, area_c );
+	result = vips_call_split( "math2_const", ap, in, out, math2, area_c );
 
 	vips_area_unref( area_c );