Mercurial > octave-nkf
comparison scripts/general/logspace.m @ 4:b4df021f796c
[project @ 1993-08-08 01:26:08 by jwe]
Initial revision
| author | jwe |
|---|---|
| date | Sun, 08 Aug 1993 01:26:08 +0000 |
| parents | |
| children | 16a24e76d6e0 |
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| 3:9a4c07481e61 | 4:b4df021f796c |
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| 1 function retval = logspace (x1, x2, n) | |
| 2 | |
| 3 # usage: logspace (x1, x2, n) | |
| 4 # | |
| 5 # Return a vector of n logarithmically equally spaced points between | |
| 6 # x1 and x2 inclusive. | |
| 7 # | |
| 8 # If the final argument is omitted, n = 50 is assumed. | |
| 9 # | |
| 10 # All three arguments must be scalars. | |
| 11 # | |
| 12 # Note that if if x2 is pi, the points are between 10^x1 and pi, NOT | |
| 13 # 10^x1 and 10^pi. | |
| 14 # | |
| 15 # Yes, this is pretty stupid, because you could achieve the same | |
| 16 # result with logspace (x1, log10 (pi)), but Matlab does this, and | |
| 17 # claims that is useful for signal processing applications. | |
| 18 # | |
| 19 # See also: linspace | |
| 20 | |
| 21 if (nargin == 2) | |
| 22 npoints = 50; | |
| 23 elseif (nargin == 3) | |
| 24 if (length (n) == 1) | |
| 25 npoints = n; | |
| 26 else | |
| 27 error ("logspace: arguments must be scalars"); | |
| 28 endif | |
| 29 else | |
| 30 error ("usage: logspace (x1, x2 [, n])"); | |
| 31 endif | |
| 32 | |
| 33 if (npoints < 2) | |
| 34 error ("logspace: npoints must be greater than 2"); | |
| 35 endif | |
| 36 | |
| 37 if (length (x1) == 1 && length (x2) == 1) | |
| 38 x2_tmp = x2; | |
| 39 if (x2 == pi) | |
| 40 x2_tmp = log10 (pi); | |
| 41 endif | |
| 42 retval = linspace (x1, x2_tmp, npoints); | |
| 43 for i = 1:npoints | |
| 44 retval(i) = 10 ^ retval(i); | |
| 45 endfor | |
| 46 else | |
| 47 error ("logspace: arguments must be scalars"); | |
| 48 endif | |
| 49 | |
| 50 endfunction |