Programmer Guide/Command Reference/EVAL/dft: Difference between revisions

Revision as of 12:02, 12 April 2011

Inverse or forward discrete fourier transform (dft).

Usage

dft(x {, type)

xthe data vector to be transformed
type: selects the data type of the argument and result and the transformation to be performed (default=0)

Result: A vector y containing the result of the transformation. The length and content of y depends on x and type.

type	x	nrow(x)	y	nrow(y)	description
0	real signal with N samples	N	complex spectrum with N/2+1 values	N+2	`real->complex` forward dft note: only the first half (values: 0..N/2) of the conj. sym. complex spectrum is stored in y
1	complex signal with N samples	2N	complex spectrum with N values	2N	`complex->complex` forward dft
2	first half (values: 0..N/2) of a conj. sym. complex spectrum	N+2	real signal with N samples	N	`complex->real` inverse dft note: the inverse of type=0
3	complex spectrum with N values	2N	complex signal with N samples	2N	`complex->complex` inverse dft

@@ Line 13: / Line 13: @@
 |complex spectrum with N/2+1 values
 |N+2
-|'''real->complex''' forward dft<BR>note: only the first half (values: 0..N/2) of the conj. sym. complex spectrum is stored in ''y''
+|<code>real->complex</code> forward dft<BR>note: only the first half (values: 0..N/2) of the conj. sym. complex spectrum is stored in ''y''
 |-
 |'''1'''
@@ Line 20: / Line 20: @@
 |complex spectrum with N values
 |2N
-|'''complex->complex''' forward dft
+|<code>complex->complex</code> forward dft
 |-
 |'''2'''
@@ Line 27: / Line 27: @@
 |real signal with N samples
 |N
-|'''complex->real''' inverse dft<BR>note: the inverse of ''type''=0
+|<code>complex->real</code> inverse dft<BR>note: the inverse of ''type''=0
 |-
 |'''3'''
@@ Line 34: / Line 34: @@
 |complex signal with N samples
 |2N
-|'''complex->complex''' inverse dft
+|<code>complex->complex</code> inverse dft
 |-
 |}