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{ RCSid $Id$ } |
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{ |
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Compute Venetian Blinds angle to exclude direct sun. |
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3/19/93 |
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|
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Formula by Kostantinos Papamichael, |
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Translated by Greg Ward and Saba Rofchaei |
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} |
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{ |
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Input variables are solar altitude and azimuth in degrees: |
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|
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SALT - solar altitude (degrees) |
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SAZI - solar azimuth (degrees from South, West is positive) |
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} |
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L = .625; {slat's width} |
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D = .45833; {distance between slats} |
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ORIENT = 0.0; { Window orientation } |
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DEGREE : PI/180.0; |
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|
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tan_lambda = tan(SALT*DEGREE) / cos((SAZI+ORIENT)*DEGREE); |
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lambda = atan(tan_lambda) / DEGREE; |
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a = tan_lambda*tan_lambda + 1.0; |
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b = -2.0*(D/L); |
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c = (D/L)*(D/L) - tan_lambda*tan_lambda; |
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det = sqrt(b*b - 4.0*a*c); |
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{calculating slats' angle corresponding to solar position} |
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POS1 = asin((-b+det)/(2.0*a)) / DEGREE; |
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POS2 = asin((-b-det)/(2.0*a)) / DEGREE; |
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