convol - convolution

Calling Sequence

[y]=convol(h,x)

[y,e1]=convol(h,x,e0)

Parameters

• x,h :input sequences (h is a "short" sequence, x a "long" one)
• e0 : old tail to overlap add (not used in first call)
• y : output of convolution
• e1 : new tail to overlap add (not used in last call)

Description

calculates the convolution y= h*x of two discrete sequences by using the fft. Overlap add method can be used.

USE OF OVERLAP ADD METHOD: For x=[x1,x2,...,xNm1,xN] First call is [y1,e1]=convol(h,x1); Subsequent calls : [yk,ek]=convol(h,xk,ekm1); Final call : [yN]=convol(h,xN,eNm1); Finally y=[y1,y2,...,yNm1,yN]

Examples

x=1:3;
h1=[1,0,0,0,0];h2=[0,1,0,0,0];h3=[0,0,1,0,0];
x1=convol(h1,x),x2=convol(h2,x),x3=convol(h3,x),
convol(h1+h2+h3,x)
p1=poly(x,'x','coeff')
p2=poly(h1+h2+h3,'x','coeff')
p1*p2
 

See Also

corr  fft  pspect  

Author

F. D , C. Bunks Date 3 Oct. 1988; ;