Air mass: Difference between revisions
Added C solution
(Added Java solution) |
(Added C solution) |
||
Line 78:
90 34.32981136 34.36666557
</pre>
=={{header|C}}==
{{trans|FreeBASIC}}
<lang c>#include <math.h>
#include <stdio.h>
#define DEG 0.017453292519943295769236907684886127134 // degrees to radians
#define RE 6371000.0 // Earth radius in meters
#define DD 0.001 // integrate in this fraction of the distance already covered
#define FIN 10000000.0 // integrate only to a height of 10000km, effectively infinity
static double rho(double a) {
// the density of air as a function of height above sea level
return exp(-a / 8500.0);
}
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 = sqrt(aa * aa + d * d - 2.0 * d * aa * cos((180 - z) * DEG));
return hh - RE;
}
static double column_density(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 = DD * d;
if (delta < DD)
delta = DD;
sum += rho(height(a, z, d + 0.5 * delta)) * delta;
d += delta;
}
return sum;
}
static double airmass(double a, double z) {
return column_density(a, z) / column_density(a, 0.0);
}
int main() {
puts("Angle 0 m 13700 m");
puts("------------------------------------");
for (double z = 0; z <= 90; z+= 5) {
printf("%2.0f %11.8f %11.8f\n",
z, airmass(0.0, z), airmass(13700.0, z));
}
}</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|Factor}}==
{{trans|FreeBASIC}}
| |||