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1 function y = polyvalm(c,x) |
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2 |
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3 # Evaluate a polynomial in the matrix sense. |
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4 # |
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5 # In octave, a polynomial is represented by it's coefficients (arranged |
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6 # in descending order). For example a vector c of length n+1 corresponds |
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7 # to the following nth order polynomial |
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8 # |
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9 # p(x) = c(1) x^n + ... + c(n) x + c(n+1). |
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10 # |
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11 # polyvalm(c,X) will evaluate the polynomial in the matrix sense, i.e. matrix |
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12 # multiplication is used instead of element by element multiplication as is |
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13 # used in polyval. |
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14 # |
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15 # X must be a square matrix. |
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16 # |
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17 # SEE ALSO: polyval, poly, roots, conv, deconv, residue, filter, |
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18 # polyderiv, polyinteg |
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19 |
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20 # Author: |
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21 # Tony Richardson |
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22 # amr@mpl.ucsd.edu |
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23 # June 1994 |
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24 |
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25 if(nargin != 2) |
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26 usage ("polyvalm(c,x)"); |
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27 endif |
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28 |
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29 if(is_matrix(c)) |
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30 error("poly: first argument must be a vector."); |
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31 endif |
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32 |
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33 if(!is_square(x)) |
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34 error("poly: second argument must be a square matrix."); |
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35 endif |
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36 |
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37 [v, d] = eig(x); |
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38 |
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39 y = v * diag(polyval(c,diag(d))) * v'; |
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40 |
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41 endfunction |
