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Last change
on this file since 163 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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