Mercurial > hg > octave-lyh
comparison scripts/polynomial/conv.m @ 787:c5d35bb139b6
[project @ 1994-10-11 00:34:13 by jwe]
Initial revision
| author | jwe |
|---|---|
| date | Tue, 11 Oct 1994 00:34:39 +0000 |
| parents | |
| children | 3470f1e25a79 |
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| 786:4fcd2e68dd3b | 787:c5d35bb139b6 |
|---|---|
| 1 function y = conv (a, b) | |
| 2 | |
| 3 # Convolve two vectors. | |
| 4 # y = conv (a, b) returns a vector of length equal to length (a) + | |
| 5 # length (b) -1. | |
| 6 # If a and b are polynomial coefficient vectors, conv returns the | |
| 7 # coefficients of the product polynomial. | |
| 8 # | |
| 9 # SEE ALSO: deconv, poly, roots, residue, polyval, polyderiv, | |
| 10 # polyinteg | |
| 11 | |
| 12 # Author: | |
| 13 # Tony Richardson | |
| 14 # amr@mpl.ucsd.edu | |
| 15 # June 1994 | |
| 16 | |
| 17 if (nargin != 2) | |
| 18 error ("usage: conv(a,b)"); | |
| 19 endif | |
| 20 | |
| 21 if (is_matrix(a) || is_matrix(b)) | |
| 22 error("conv: both arguments must be vectors"); | |
| 23 endif | |
| 24 | |
| 25 la = length (a); | |
| 26 lb = length (b); | |
| 27 | |
| 28 ly = la + lb - 1; | |
| 29 | |
| 30 # Ensure that both vectors are row vectors. | |
| 31 if (rows (a) > 1) | |
| 32 a = reshape (a, 1, la); | |
| 33 endif | |
| 34 if (rows (b) > 1) | |
| 35 b = reshape (b, 1, lb); | |
| 36 endif | |
| 37 | |
| 38 # Use the shortest vector as the coefficent vector to filter. | |
| 39 if (la < lb) | |
| 40 if (ly > lb) | |
| 41 x = [b zeros (1, ly - lb)]; | |
| 42 else | |
| 43 x = b; | |
| 44 endif | |
| 45 y = filter (a, 1, x); | |
| 46 else | |
| 47 if(ly > la) | |
| 48 x = [a zeros (1, ly - la)]; | |
| 49 else | |
| 50 x = a; | |
| 51 endif | |
| 52 y = filter (b, 1, x); | |
| 53 endif | |
| 54 | |
| 55 endfunction |