Enhanced Ellipsoid Models for SasView - core_shell_ellipsoid_high_res_integration.c

    ##include <stdio.h>


#define min(a,b) ((a) < (b) ? (a) : (b))
#define max(a,b) ((a) > (b) ? (a) : (b))

const double coeffs[] = {0.0, 0.3150863379101902, 0.16613470175179204, 0.16613470175177467, 0.16613470175177394, 0.1661347017517684, 0.024856896057016388, 0.013270720644418109, 0.013270720644418034, 0.013270720644418244, 0.013270720644418057, 0.0035682981688967726, -0.022708438650798857, 0.012140265072473113, 0.012140265072473217, 0.0035682981688967158, 0.012140265072473257, 0.012140265072473266, 0.00356829816889676, -0.02270843865079874, 0.003568298168896832};
const double intercept = 0.8658426289390544;
const double limits[][2] = {{5e-05, 1.0}, {1.0, 1000000.0}, {1.0, 1000000.0}, {1.0, 1000000.0}, {1.0, 1000000.0}};


inline float log2m (float val)
{
   int * const    exp_ptr = (int *) (&val);
   int            x = *exp_ptr;
   const int      log_2 = ((x >> 23) & 255) - 128;
   x &= ~(255 << 23);
   x += 127 << 23;
   *exp_ptr = x;

   val = ((-1.0f/3) * val + 2) * val - 2.0f/3;   // (1)

   return (val + log_2);
}



double eval_poly(double var0, double var1, double var2, double var3, double var4){
    return 1 * coeffs[0] + var0 * coeffs[1] + var1 * coeffs[2] + var2 * coeffs[3] + var3 * coeffs[4] + var4 * coeffs[5] + (var0 * var0) * coeffs[6] + var0 * var1 * coeffs[7] + var0 * var2 * coeffs[8] + var0 * var3 * coeffs[9] + var0 * var4 * coeffs[10] + (var1 * var1) * coeffs[11] + var1 * var2 * coeffs[12] + var1 * var3 * coeffs[13] + var1 * var4 * coeffs[14] + (var2 * var2) * coeffs[15] + var2 * var3 * coeffs[16] + var2 * var4 * coeffs[17] + (var3 * var3) * coeffs[18] + var3 * var4 * coeffs[19] + (var4 * var4) * coeffs[20] + intercept;
}
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