Last change
on this file since 25 was
25,
checked in by pinsard, 18 years ago
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upgrade of CALCULS according to cerbere.lodyc.jussieu.fr: /usr/home/smasson/SAXO_RD/ : files
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-
Property svn:executable set to
*
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File size:
957 bytes
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Line | |
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1 | ;+ |
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2 | ; NAME:determ2 |
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3 | ; |
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4 | ; PURPOSE: computes the determinant of n 2 by 2 arrays |
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5 | ; |
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6 | ; CATEGORY: no DO loops and better accuracy |
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7 | ; |
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8 | ; CALLING SEQUENCE: 2 cases: |
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9 | ; res = determ2(z2ds) |
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10 | ; res = determ2(z1d00,z1d01,z1d10,z1d11) |
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11 | ; |
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12 | ; INPUTS: |
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13 | ; z2ds: an 2*2*n array |
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14 | ; or |
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15 | ; z1d00,z1d01,z1d10,z1d11: the four n elements arrays |
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16 | ; defined as: |
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17 | ; z2ds[0, 0, *] = z1d00 |
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18 | ; z2ds[0, 1, *] = z1d01 |
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19 | ; z2ds[1, 0, *] = z1d10 |
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20 | ; z2ds[1, 1, *] = z1d11 |
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21 | ; |
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22 | ; OUTPUTS: n elements array, the determinent of each 2*2 arrrays |
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23 | ; |
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24 | ; EXAMPLE: |
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25 | ; |
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26 | ; a=findgen(2,2,5) |
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27 | ; print, determ2(a) |
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28 | ; FOR i=0,4 DO print, determ(a[*,*,i]) ; IDL solution |
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29 | ; |
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30 | ; MODIFICATION HISTORY: |
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31 | ; S. Masson (smasson@lodyc.jussieu.fr) |
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32 | ; July 11th, 2002 |
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33 | ;- |
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34 | FUNCTION determ2, a, b, c, d |
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35 | CASE n_params() OF |
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36 | 1:res = a[0, 0, *]*a[1, 1, *]-a[0, 1, *]*a[1, 0, *] |
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37 | 4:res = a[*]*d[*]-c[*]*b[*] |
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38 | ELSE:stop |
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39 | ENDCASE |
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40 | |
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41 | RETURN, res |
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42 | END |
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