Last change
on this file since 177 was
163,
checked in by navarro, 18 years ago
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header improvements : type of parameters and keywords, default values, spell checking + idldoc assistant (IDL online_help)
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Property svn:eol-style set to
native
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Property svn:keywords set to
Id
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File size:
887 bytes
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1 | ;+ |
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2 | ; |
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3 | ; @file_comments |
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4 | ; Rotate two vectors by a specified amount. |
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5 | ; |
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6 | ; @param X {in}{required} |
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7 | ; original data point pairs |
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8 | ; |
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9 | ; @param Y {in}{required} |
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10 | ; original data point pairs |
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11 | ; |
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12 | ; @param DEG {in}{required} |
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13 | ; degrees to rotate. |
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14 | ; |
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15 | ; @param NX {out} |
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16 | ; rotated point pairs. |
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17 | ; |
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18 | ; @param NY {out} |
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19 | ; rotated point pairs. |
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20 | ; |
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21 | ; @history |
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22 | ; Jeff Bennett, U of Colorado |
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23 | ; |
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24 | ; @version |
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25 | ; $Id$ |
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26 | ; |
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27 | ;- |
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28 | |
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29 | PRO rotation,X,Y,DEG,NX,NY |
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30 | ; |
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31 | compile_opt idl2, strictarrsubs |
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32 | ; |
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33 | ang=deg*!dtor |
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34 | |
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35 | ;convert to polar coordinates for rotation |
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36 | r = sqrt(x*x + y*y) |
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37 | theta = r*0. |
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38 | ;get angle in for loop so that zero radii will be left as zero angle |
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39 | for i = 0,n_elements(r)-1 do $ |
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40 | if r[i] ne 0 then theta[i] = atan(y[i],x[i]) ;range from -pi to +pi |
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41 | ; |
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42 | ;add rotation angle |
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43 | theta = theta + ang |
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44 | ; |
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45 | ;convert back to rectangular coordinates, now rotated |
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46 | nx = r * cos(theta) |
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47 | ny = r * sin(theta) |
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48 | ; |
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49 | return |
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50 | end |
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