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.TH "fft1d" 2 " July 3rd 1997" "Fractales Group" "Scilab Function"
.so ../sci.an
.SH NAME
fft1d - Operates a column-wise direct or inverse FFT
.sp
Author: Paulo Goncalves
.sp
Operates a column-wise direct or inverse FFT on a matrix
.sp
.sp
.SH Usage
.sp
.ft CR
.nf
Y = fft1d(X,DirInv) ;
.fi
.ec
.ft P
.sp
.SH Input parameters
.RS
.TP
o
\fBX\fP : Real or complex valued matrix \f(CR[\fPrx,cx\f(CR]\fP
.TP
o
\fBDirInv\fP : +1 / -1 flag
-1 Direct Fast Fourier Transform
+1 Inverse Fast Fourier Transform
.RE
.SH Output parameters
.RS
.TP
o
\fBY\fP : Real or complex valued matrix \f(CR[\fPrx,cx\f(CR]\fP
Each column of \fIY\fP contains the FFT (resp IFFT) of the corresponding column of \fIX\fP
.RE
.SH See also:
fft
.SH Example:
\fI Matrix synthesis: \fP
.sp
.ft CR
.nf
t = linspace( 0,1,128 ) ;
f0 = [4 8 16 32]
X = sin( 2*%pi*t(:)*f0 ) ;
Y = abs( fft1d( X , -1 ) ) ;
Y = [Y(65:128,:) ; Y(1:64,:)] ;
f = linspace(-64,63,128) ;
plot2d(f(ones(4,1),:)',Y) ;
.fi
.ec
.ft P
.sp
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