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1 /* |
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2 |
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3 Copyright (C) 1996, 1997 John W. Eaton |
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4 |
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5 This file is part of Octave. |
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6 |
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7 Octave is free software; you can redistribute it and/or modify it |
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8 under the terms of the GNU General Public License as published by the |
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9 Free Software Foundation; either version 2, or (at your option) any |
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10 later version. |
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11 |
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12 Octave is distributed in the hope that it will be useful, but WITHOUT |
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13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
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15 for more details. |
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16 |
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17 You should have received a copy of the GNU General Public License |
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18 along with Octave; see the file COPYING. If not, write to the Free |
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19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
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20 |
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21 */ |
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22 |
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23 // Based on Tony Richardson's filter.m. |
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24 // |
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25 // Originally translated to C++ by KH (Kurt.Hornik@ci.tuwien.ac.at) |
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26 // with help from Fritz Leisch and Andreas Weingessel on Oct 20, 1994. |
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27 // |
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28 // Rewritten to use templates to handle both real and complex cases by |
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29 // jwe, Wed Nov 1 19:15:29 1995. |
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30 |
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31 #ifdef HAVE_CONFIG_H |
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32 #include <config.h> |
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33 #endif |
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34 |
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35 #include "defun-dld.h" |
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36 #include "error.h" |
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37 #include "oct-obj.h" |
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38 #include "help.h" |
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39 |
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40 extern MArray<double> |
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41 filter (MArray<double>&, MArray<double>&, MArray<double>&); |
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42 |
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43 extern MArray<Complex> |
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44 filter (MArray<Complex>&, MArray<Complex>&, MArray<Complex>&); |
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45 |
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46 template <class T> |
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47 MArray<T> |
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48 filter (MArray<T>& b, MArray<T>& a, MArray<T>& x, MArray<T>& si) |
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49 { |
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50 MArray<T> y; |
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51 |
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52 int a_len = a.length (); |
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53 int b_len = b.length (); |
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54 int x_len = x.length (); |
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55 |
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56 int si_len = si.length (); |
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57 |
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58 int ab_len = a_len > b_len ? a_len : b_len; |
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59 |
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60 b.resize (ab_len, 0.0); |
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61 |
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62 if (si.length () != ab_len - 1) |
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63 { |
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64 error ("filter: si must be a vector of length max (length (a), length (b)) - 1"); |
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65 return y; |
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66 } |
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67 |
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68 T norm = a (0); |
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69 |
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70 if (norm == 0.0) |
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71 { |
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72 error ("filter: the first element of a must be non-zero"); |
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73 return y; |
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74 } |
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75 |
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76 y.resize (x_len, 0.0); |
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77 |
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78 if (norm != 1.0) |
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79 b = b / norm; |
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80 |
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81 if (a_len > 1) |
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82 { |
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83 a.resize (ab_len, 0.0); |
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84 |
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85 if (norm != 1.0) |
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86 a = a / norm; |
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87 |
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88 for (int i = 0; i < x_len; i++) |
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89 { |
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90 y (i) = si (0) + b (0) * x (i); |
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91 |
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92 if (si_len > 1) |
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93 { |
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94 for (int j = 0; j < si_len - 1; j++) |
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95 si (j) = si (j+1) - a (j+1) * y (i) |
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96 + b (j+1) * x (i); |
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97 |
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98 si (si_len-1) = b (si_len) * x (i) |
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99 - a (si_len) * y (i); |
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100 } |
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101 else |
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102 si (0) = b (si_len) * x (i) |
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103 - a (si_len) * y (i); |
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104 } |
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105 } |
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106 else if (si_len > 0) |
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107 { |
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108 for (int i = 0; i < x_len; i++) |
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109 { |
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110 y (i) = si (0) + b (0) * x (i); |
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111 |
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112 if (si_len > 1) |
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113 { |
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114 for (int j = 0; j < si_len - 1; j++) |
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115 si (j) = si (j+1) + b (j+1) * x (i); |
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116 |
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117 si (si_len-1) = b (si_len) * x (i); |
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118 } |
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119 else |
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120 si (0) = b (1) * x (i); |
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121 } |
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122 } |
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123 else |
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124 y = b (0) * x; |
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125 |
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126 return y; |
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127 } |
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128 |
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129 extern MArray<double> |
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130 filter (MArray<double>&, MArray<double>&, MArray<double>&, |
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131 MArray<double>&); |
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132 |
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133 extern MArray<Complex> |
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134 filter (MArray<Complex>&, MArray<Complex>&, MArray<Complex>&, |
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135 MArray<Complex>&); |
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136 |
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137 template <class T> |
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138 MArray<T> |
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139 filter (MArray<T>& b, MArray<T>& a, MArray<T>& x) |
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140 { |
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141 int a_len = a.length (); |
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142 int b_len = b.length (); |
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143 |
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144 int si_len = (a_len > b_len ? a_len : b_len) - 1; |
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145 |
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146 MArray<T> si (si_len, T (0.0)); |
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147 |
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148 return filter (b, a, x, si); |
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149 } |
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150 |
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151 DEFUN_DLD (filter, args, , |
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152 "usage: [y [, sf]] = filter (b, a, x [, si])\n\ |
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153 \n\ |
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154 y = filter (b, a, x) returns the solution to the following linear,\n\ |
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155 time-invariant difference equation:\n\ |
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156 \n\ |
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157 a[1] y[n] + ... + a[la] y[n-la+1] = b[1] x[n] + ... + b[lb] x[n-lb+1],\n\ |
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158 where la = length (a) and lb = length (b).\n\ |
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159 \n\ |
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160 [y, sf] = filter (b, a, x, si) sets the initial state of the system, si,\n\ |
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161 and returns the final state, sf. The state vector is a column vector\n\ |
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162 whose length is equal to the length of the longest coefficient vector\n\ |
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163 minus one. If si is not set, the initial state vector is set to all\n\ |
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164 zeros.\n\ |
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165 \n\ |
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166 The particular algorithm employed is known as a transposed Direct Form II\n\ |
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167 implementation.") |
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168 { |
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169 octave_value_list retval; |
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170 |
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171 int nargin = args.length (); |
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172 |
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173 if (nargin < 3 || nargin > 4) |
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174 { |
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175 print_usage ("filter"); |
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176 return retval; |
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177 } |
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178 |
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179 const char *errmsg = "filter: arguments must be vectors"; |
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180 |
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181 int x_is_vector = (args(2).rows () == 1 || args(2).columns () == 1); |
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182 |
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183 int si_is_vector = (nargin == 4 |
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184 && (args(3).rows () == 1 || args(3).columns () == 1)); |
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185 |
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186 if (args(0).is_complex_type () |
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187 || args(1).is_complex_type () |
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188 || args(2).is_complex_type () |
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189 || (nargin == 4 && args(3).is_complex_type ())) |
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190 { |
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191 ComplexColumnVector b = args(0).complex_vector_value (); |
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192 ComplexColumnVector a = args(1).complex_vector_value (); |
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193 ComplexColumnVector x = args(2).complex_vector_value (); |
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194 |
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195 if (! error_state) |
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196 { |
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197 if (nargin == 3) |
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198 { |
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199 ComplexColumnVector y (filter (b, a, x)); |
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200 |
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201 if (x_is_vector) |
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202 retval (0) = octave_value (y, (args(2).columns () == 1)); |
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203 else |
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204 retval (0) = y; |
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205 } |
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206 else |
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207 { |
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208 ComplexColumnVector si = args(3).complex_vector_value (); |
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209 |
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210 if (! error_state) |
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211 { |
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212 ComplexColumnVector y (filter (b, a, x, si)); |
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213 |
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214 if (si_is_vector) |
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215 retval (1) = octave_value (si, (args(3).columns () == 1)); |
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216 else |
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217 retval (1) = si; |
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218 |
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219 if (x_is_vector) |
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220 retval (0) = octave_value (y, (args(2).columns () == 1)); |
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221 else |
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222 retval (0) = y; |
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223 } |
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224 else |
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225 error (errmsg); |
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226 } |
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227 } |
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228 else |
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229 error (errmsg); |
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230 } |
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231 else |
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232 { |
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233 ColumnVector b = args(0).vector_value (); |
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234 ColumnVector a = args(1).vector_value (); |
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235 ColumnVector x = args(2).vector_value (); |
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236 |
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237 if (! error_state) |
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238 { |
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239 if (nargin == 3) |
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240 { |
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241 ColumnVector y (filter (b, a, x)); |
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242 |
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243 if (x_is_vector) |
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244 retval (0) = octave_value (y, (args(2).columns () == 1)); |
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245 else |
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246 retval (0) = y; |
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247 } |
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248 else |
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249 { |
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250 ColumnVector si = args(3).vector_value (); |
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251 |
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252 if (! error_state) |
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253 { |
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254 ColumnVector y (filter (b, a, x, si)); |
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255 |
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256 if (si_is_vector) |
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257 retval (1) = octave_value (si, (args(3).columns () == 1)); |
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258 else |
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259 retval (1) = si; |
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260 |
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261 if (x_is_vector) |
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262 retval (0) = octave_value (y, (args(2).columns () == 1)); |
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263 else |
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264 retval (0) = y; |
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265 } |
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266 else |
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267 error (errmsg); |
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268 } |
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269 } |
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270 else |
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271 error (errmsg); |
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272 } |
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273 |
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274 return retval; |
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275 } |
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276 |
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277 template MArray<double> |
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278 filter (MArray<double>&, MArray<double>&, MArray<double>&, |
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279 MArray<double>&); |
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280 |
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281 template MArray<double> |
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282 filter (MArray<double>&, MArray<double>&, MArray<double>&); |
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283 |
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284 template MArray<Complex> |
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285 filter (MArray<Complex>&, MArray<Complex>&, MArray<Complex>&, |
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286 MArray<Complex>&); |
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287 |
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288 template MArray<Complex> |
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289 filter (MArray<Complex>&, MArray<Complex>&, MArray <Complex>&); |
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290 |
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291 /* |
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292 ;;; Local Variables: *** |
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293 ;;; mode: C++ *** |
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294 ;;; End: *** |
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295 */ |
