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1 ## Copyright (C) 1993, 1994, 1995 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 |
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7 ## the Free Software Foundation; either version 3 of the License, or (at |
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8 ## your option) any later version. |
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9 ## |
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10 ## Octave is distributed in the hope that it will be useful, but |
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of |
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
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13 ## General Public License 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, see |
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17 ## <http://www.gnu.org/licenses/>. |
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18 |
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19 ## -*- texinfo -*- |
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20 ## @deftypefn {Function File} {} damp (@var{p}, @var{tsam}) |
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21 ## Displays eigenvalues, natural frequencies and damping ratios |
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22 ## of the eigenvalues of a matrix @var{p} or the @math{A} matrix of a |
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23 ## system @var{p}, respectively. |
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24 ## If @var{p} is a system, @var{tsam} must not be specified. |
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25 ## If @var{p} is a matrix and @var{tsam} is specified, eigenvalues |
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26 ## of @var{p} are assumed to be in @var{z}-domain. |
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27 ## @seealso{eig} |
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28 ## @end deftypefn |
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29 |
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30 ## Author: Kai P. Mueller <mueller@ifr.ing.tu-bs.de> |
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31 ## Created: September 29, 1997. |
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32 |
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33 function damp (p, tsam) |
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34 |
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35 ## assume a continuous system |
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36 DIGITAL = 0; |
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37 if(nargin < 1 || nargin > 2) |
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38 print_usage (); |
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39 endif |
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40 if(isstruct(p)) |
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41 if (nargin != 1) |
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42 error("damp: when p is a system, tsamp parameter is not allowed."); |
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43 endif |
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44 [aa, b, c, d, t_samp] = sys2ss(p); |
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45 DIGITAL = is_digital(p); |
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46 else |
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47 aa = p; |
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48 if (nargin == 2) |
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49 DIGITAL = 1; |
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50 t_samp = tsam; |
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51 endif |
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52 endif |
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53 if (!issquare(aa)) |
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54 error("damp: Matrix p is not square.") |
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55 endif |
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56 if (DIGITAL && t_samp <= 0.0) |
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57 error("damp: Sampling time tsam must not be <= 0.") |
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58 endif |
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59 |
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60 ## all checks done. |
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61 e = eig(aa); |
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62 [n, m] = size(aa); |
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63 if (DIGITAL) |
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64 printf(" (discrete system with sampling time %f)\n", t_samp); |
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65 endif |
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66 printf("............... Eigenvalue ........... Damping Frequency\n"); |
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67 printf("--------[re]---------[im]--------[abs]----------------------[Hz]\n"); |
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68 for i = 1:n |
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69 pole = e(i); |
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70 cpole = pole; |
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71 if (DIGITAL) |
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72 cpole = log(pole) / t_samp; |
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73 endif |
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74 d0 = -cos(atan2(imag(cpole), real(cpole))); |
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75 f0 = 0.5 / pi * abs(cpole); |
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76 if (abs(imag(cpole)) < eps) |
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77 printf("%12f --- %12f %10f %12f\n", |
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78 real(pole), abs(pole), d0, f0); |
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79 else |
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80 printf("%12f %12f %12f %10f %12f\n", |
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81 real(pole), imag(pole), abs(pole), d0, f0); |
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82 endif |
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83 endfor |
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84 |
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85 endfunction |
