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1 # Copyright (C) 1993, 1994 John W. Eaton |
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2 # |
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3 # This file is part of Octave. |
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4 # |
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5 # Octave is free software; you can redistribute it and/or modify it |
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6 # under the terms of the GNU General Public License as published by the |
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7 # Free Software Foundation; either version 2, or (at your option) any |
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8 # later version. |
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9 # |
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10 # Octave is distributed in the hope that it will be useful, but WITHOUT |
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11 # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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12 # FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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13 # for more details. |
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14 # |
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15 # You should have received a copy of the GNU General Public License |
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16 # along with Octave; see the file COPYING. If not, write to the Free |
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17 # Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. |
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18 |
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4
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19 function retval = logspace (x1, x2, n) |
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20 |
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21 # usage: logspace (x1, x2, n) |
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22 # |
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23 # Return a vector of n logarithmically equally spaced points between |
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24 # x1 and x2 inclusive. |
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25 # |
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26 # If the final argument is omitted, n = 50 is assumed. |
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27 # |
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28 # All three arguments must be scalars. |
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29 # |
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30 # Note that if if x2 is pi, the points are between 10^x1 and pi, NOT |
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31 # 10^x1 and 10^pi. |
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32 # |
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33 # Yes, this is pretty stupid, because you could achieve the same |
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34 # result with logspace (x1, log10 (pi)), but Matlab does this, and |
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35 # claims that is useful for signal processing applications. |
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36 # |
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37 # See also: linspace |
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38 |
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39 if (nargin == 2) |
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40 npoints = 50; |
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41 elseif (nargin == 3) |
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42 if (length (n) == 1) |
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43 npoints = fix (n); |
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4
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44 else |
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45 error ("logspace: arguments must be scalars"); |
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46 endif |
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47 else |
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48 error ("usage: logspace (x1, x2 [, n])"); |
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49 endif |
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50 |
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51 if (npoints < 2) |
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52 error ("logspace: npoints must be greater than 2"); |
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53 endif |
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54 |
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55 if (length (x1) == 1 && length (x2) == 1) |
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56 x2_tmp = x2; |
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57 if (x2 == pi) |
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58 x2_tmp = log10 (pi); |
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59 endif |
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60 retval = 10 .^ (linspace (x1, x2_tmp, npoints)); |
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61 else |
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62 error ("logspace: arguments must be scalars"); |
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63 endif |
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64 |
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65 endfunction |
