1 | ;+ |
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2 | ; |
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3 | ; file_comments |
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4 | ; computes the determinant of n 2 by 2 arrays |
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5 | ; Z2DS is an 2*2*n array |
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6 | ; |
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7 | ; @categories |
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8 | ; Without loop |
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9 | ; |
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10 | ; @param A {in}{required} |
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11 | ; n element array |
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12 | ; Defined as z2ds[0, 0, *] = z1d00 |
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13 | ; |
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14 | ; @param B {in}{required} |
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15 | ; n element array |
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16 | ; Defined as z2ds[0, 1, *] = z1d01 |
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17 | ; |
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18 | ; @param C {in}{required} |
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19 | ; n element array |
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20 | ; Defined as z2ds[1, 0, *] = z1d10 |
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21 | ; |
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22 | ; @param D {in}{required} |
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23 | ; n element array |
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24 | ; Defined as z2ds[1, 1, *] = z1d11 |
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25 | ; |
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26 | ; @returns |
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27 | ; n elements array, the determinent of each 2*2 arrrays |
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28 | ; |
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29 | ; @examples |
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30 | ; a=findgen(2,2,5) |
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31 | ; print, determ2(a) |
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32 | ; FOR i=0,4 DO print, determ(a[*,*,i]) ; IDL solution |
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33 | ; |
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34 | ; @history |
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35 | ; S. Masson (smasson\@lodyc.jussieu.fr) |
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36 | ; July 11th, 2002 |
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37 | ; |
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38 | ; @version |
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39 | ; $Id$ |
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40 | ; |
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41 | ;- |
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42 | FUNCTION determ2, a, b, c, d |
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43 | ; |
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44 | compile_opt idl2, strictarrsubs |
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45 | ; |
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46 | CASE n_params() OF |
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47 | 1:res = a[0, 0, *]*a[1, 1, *]-a[0, 1, *]*a[1, 0, *] |
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48 | 4:res = a[*]*d[*]-c[*]*b[*] |
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49 | ELSE:stop |
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50 | ENDCASE |
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51 | |
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52 | RETURN, res |
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53 | END |
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