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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 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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19 function damp(p, tsam) |
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20 # Usage: damp(p[, tsam]) |
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21 # Displays eigenvalues, natural frequencies and damping ratios |
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22 # of the eigenvalues of a matrix p or the A-matrix of a |
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23 # system p, respectively. |
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24 # If p is a system, tsam must not be specified. |
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25 # If p is a matrix and tsam is specified, eigenvalues |
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26 # of p are assumed to be in z-domain. |
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27 # |
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28 # See also: eig |
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29 |
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30 # Written by Kai P. Mueller September 29, 1997. |
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31 # Update |
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32 |
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33 # assume a continuous system |
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34 DIGITAL = 0; |
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35 if(nargin < 1 || nargin > 2) |
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36 usage("damp(p,[ tsamp])") |
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37 endif |
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38 if(is_struct(p)) |
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39 if (nargin != 1) |
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40 error("damp: when p is a system, tsamp parameter is not allowed."); |
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41 endif |
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42 [aa, b, c, d, t_samp] = sys2ss(p); |
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43 DIGITAL = is_digital(p); |
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44 else |
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45 aa = p; |
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46 if (nargin == 2) |
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47 DIGITAL = 1; |
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48 t_samp = tsam; |
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49 endif |
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50 endif |
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51 if (!is_square(aa)) |
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52 error("damp: Matrix p is not square.") |
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53 endif |
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54 if (DIGITAL && t_samp <= 0.0) |
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55 error("damp: Sampling time tsam must not be <= 0.") |
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56 endif |
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57 |
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58 # all checks done. |
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59 e = eig(aa); |
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60 [n, m] = size(aa); |
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61 if (DIGITAL) |
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62 printf(" (discrete system with sampling time %f)\n", t_samp); |
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63 endif |
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64 printf("............... Eigenvalue ........... Damping Frequency\n"); |
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65 printf("--------[re]---------[im]--------[abs]----------------------[Hz]\n"); |
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66 for i = 1:n |
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67 pole = e(i); |
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68 cpole = pole; |
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69 if (DIGITAL) |
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70 cpole = log(pole) / t_samp; |
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71 endif |
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72 d0 = -cos(atan2(imag(cpole), real(cpole))); |
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73 f0 = 0.5 / pi * abs(cpole); |
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74 if (abs(imag(cpole)) < eps) |
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75 printf("%12f --- %12f %10f %12f\n", |
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76 real(pole), abs(pole), d0, f0); |
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77 else |
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78 printf("%12f %12f %12f %10f %12f\n", |
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79 real(pole), imag(pole), abs(pole), d0, f0); |
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80 endif |
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81 endfor |
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82 |
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83 endfunction |
