From 52c7d506e13dca5c92692e95aba5dfa678b2acb0 Mon Sep 17 00:00:00 2001
From: Jukka Ojanen
Date: Tue, 5 Apr 2016 14:44:51 +0300
Subject: Add notes about data layout to ffts.h
---
include/ffts.h | 20 ++++++++++++++++----
1 file changed, 16 insertions(+), 4 deletions(-)
(limited to 'include/ffts.h')
diff --git a/include/ffts.h b/include/ffts.h
index d187e36..cc85a88 100644
--- a/include/ffts.h
+++ b/include/ffts.h
@@ -56,12 +56,22 @@ extern "C" {
# endif
#endif
-#define POSITIVE_SIGN 1
-#define NEGATIVE_SIGN -1
+/* The direction of the transform
+ (i.e, the sign of the exponent in the transform.)
+*/
+#define FFTS_FORWARD (-1)
+#define FFTS_BACKWARD (+1)
struct _ffts_plan_t;
typedef struct _ffts_plan_t ffts_plan_t;
+/* Complex data is stored in the interleaved format
+ (i.e, the real and imaginary parts composing each
+ element of complex data are stored adjacently in memory)
+
+ The multi-dimensional arrays passed are expected to be
+ stored as a single contiguous block in row-major order
+*/
FFTS_API ffts_plan_t*
ffts_init_1d(size_t N, int sign);
@@ -71,8 +81,10 @@ ffts_init_2d(size_t N1, size_t N2, int sign);
FFTS_API ffts_plan_t*
ffts_init_nd(int rank, size_t *Ns, int sign);
-/* For real transforms, sign == -1 implies a real-to-complex forwards tranform,
- and sign == 1 implies a complex-to-real backwards transform.
+/* For real transforms, sign == FFTS_FORWARD implies a real-to-complex
+ forwards tranform, and sign == FFTS_BACKWARD implies a complex-to-real
+ backwards transform.
+
The output of a real-to-complex transform is N/2+1 complex numbers,
where the redundant outputs have been omitted.
*/
--
cgit v1.1