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include <math.h>
# AST_DSUN -- Distance to Sun in AU
# Taken from Astronomical Almanac 1984, page C24.
double procedure ast_dsun (epoch)
double epoch # Epoch desired
double n, g, r
double ast_julday()
begin
n = ast_julday (epoch) - 2451545d0
g = DEGTORAD (357.528d0 + 0.9856003d0 * n)
r = 1.00014d0 - 0.01671d0 * cos (g) - 0.00014d0 * cos (2 * g)
return (r)
end
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