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#include <stdlib.h>
#include <stdio.h>
#include <math.h>
 
float air_density(float alt)					//model from NASA
{    
     float temp,pres;
     if (alt < 11000.0)
     {    // below 11Km - Troposphere
          temp = 15.04 - (0.00649 * alt);
          pres = 101.29 * pow((temp + 273.1) / 288.08, 5.256); 
     }
     else
     {
         if (alt < 25000.0)
         { // between 11Km and 25Km - lower Stratosphere
              temp = -56.46;
              pres = 22.65 * exp(1.73 - ( 0.000157 * alt));
         }
         else
         { // above 25Km - upper Stratosphere
               temp = -131.21 + (0.00299 * alt);
               pres = 2.488 * pow((temp + 273.1) / 216.6, -11.388);
         }
     }
     return(pres / (0.2869 * (temp + 273.1)));
}
 
int main()
{
	int n;
	float a;
	FILE * output;
	output=fopen("sqrt_density.h","w");
	fprintf(output,"u08 sqrt_density[256]={");
	a=air_density(0);	
	for(n=0;n<256;n++)
	{
		fprintf(output,"%d,",(int)(255.0*sqrt(air_density(n*100)/a)));
	}
	fprintf(output,"};");
	fclose(output);
}