Air mass: Difference between revisions
Added Java solution
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(Added Java solution) |
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Line 264:
fmt.Printf("%2d %11.8f %11.8f\n", z, airmass(0, fz), airmass(13700, fz))
}
}</lang>
{{out}}
<pre>
Angle 0 m 13700 m
------------------------------------
0 1.00000000 1.00000000
5 1.00380963 1.00380965
10 1.01538466 1.01538475
15 1.03517744 1.03517765
20 1.06399053 1.06399093
25 1.10305937 1.10306005
30 1.15418974 1.15419083
35 1.21998076 1.21998246
40 1.30418931 1.30419190
45 1.41234169 1.41234567
50 1.55280404 1.55281025
55 1.73875921 1.73876915
60 1.99212000 1.99213665
65 2.35199740 2.35202722
70 2.89531368 2.89537287
75 3.79582352 3.79596149
80 5.53885809 5.53928113
85 10.07896219 10.08115981
90 34.32981136 34.36666557
</pre>
=={{header|Java}}==
{{trans|FreeBASIC}}
<lang java>public class AirMass {
public static void main(String[] args) {
System.out.println("Angle 0 m 13700 m");
System.out.println("------------------------------------");
for (double z = 0; z <= 90; z+= 5) {
System.out.printf("%2.0f %11.8f %11.8f\n",
z, airmass(0.0, z), airmass(13700.0, z));
}
}
private static double rho(double a) {
// the density of air as a function of height above sea level
return Math.exp(-a / 8500.0);
}
private static double height(double a, double z, double d) {
// a = altitude of observer
// z = zenith angle (in degrees)
// d = distance along line of sight
double aa = RE + a;
double hh = Math.sqrt(aa * aa + d * d - 2.0 * d * aa * Math.cos(Math.toRadians(180 - z)));
return hh - RE;
}
private static double columnDensity(double a, double z) {
// integrates density along the line of sight
double sum = 0.0, d = 0.0;
while (d < FIN) {
// adaptive step size to avoid it taking forever
double delta = Math.max(DD * d, DD);
sum += rho(height(a, z, d + 0.5 * delta)) * delta;
d += delta;
}
return sum;
}
private static double airmass(double a, double z) {
return columnDensity(a, z) / columnDensity(a, 0.0);
}
private static final double RE = 6371000.0; // Earth radius in meters
private static final double DD = 0.001; // integrate in this fraction of the distance already covered
private static final double FIN = 10000000.0; // integrate only to a height of 10000km, effectively infinity
}</lang>
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