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{ RCSid $Id$ } |
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{ |
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Compute Reinhart high-density sky patches |
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Actual density controlled by MF constant |
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Modified from Tregenza.cal |
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June 2009 G. Ward |
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} |
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DEGREE : PI/180; |
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Asin(x) : if(x-1, PI/2, if(-1-x, -PI/2, asin(x))); |
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posangle(a) : if(-a, a + 2*PI, a); |
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Atan2(y,x) : posangle(atan2(y,x)); |
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alt = Asin(Dz)/DEGREE; |
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azi = Atan2(Dx,Dy)/DEGREE; |
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MF : 2^2; { Multiplication factor } |
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alpha : 90/(MF*7 + .5); { Separation between rows in degrees } |
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{ Number of patches per row } |
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tnaz(r) : select(r, 30, 30, 24, 24, 18, 12, 6); |
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rnaz(r) : if(r-(7*MF-.5), 1, MF*tnaz(floor((r+.5)/MF) + 1)); |
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raccum(r) : if(r-.5, rnaz(r-1) + raccum(r-1), 0); |
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r_row = floor(alt/alpha); |
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r_inc = 360/rnaz(r_row); |
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r_azn = if(azi-(360-.5*r_inc), 0, floor((azi+.5*r_inc)/r_inc)); |
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rbin = if (-alt, 0, raccum(r_row) + r_azn + 1); |
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Nrbins : raccum(7*MF+1) + 1; { total number of bins } |