{
	Compute Venetian Blinds angle to exclude direct sun.

	3/19/93

	Formula by Kostantinos Papamichael,
	Translated by Greg Ward and Saba Rofchaei
}
{
	Input variables are solar altitude and azimuth in degrees:

		SALT	- solar altitude (degrees)
		SAZI	- solar azimuth (degrees from South, West is positive)
}

L = .625;    {slat's width}
D = .45833;     {distance between slats}  
ORIENT = 0.0;		{ Window orientation }
DEGREE : PI/180.0;
  
tan_lambda = tan(SALT*DEGREE) / cos((SAZI+ORIENT)*DEGREE);
lambda = atan(tan_lambda) / DEGREE;
a = tan_lambda*tan_lambda + 1.0;
b = -2.0*(D/L);
c = (D/L)*(D/L) - tan_lambda*tan_lambda;

det = sqrt(b*b - 4.0*a*c);

    {calculating slats' angle corresponding to solar position}     
POS1 = asin((-b+det)/(2.0*a)) / DEGREE;
POS2 = asin((-b-det)/(2.0*a)) / DEGREE;