update likelihood function to speed it up

This commit makes a few small changes to try and reduce the number of divisions
and multiplications done in get_expected_charge() to speed up the likelihood
function.

1 files changed, 3 insertions, 3 deletions

diff --git a/src/scattering.c b/src/scattering.c
index 2512cda..740374e 100644
--- a/src/scattering.c
+++ b/src/scattering.c
@@ -66,7 +66,7 @@ static double prob_scatter(double wavelength, void *params)
 
     delta = (1.0/index - beta_cos_theta)/beta_sin_theta_theta0;
 
-    return qe*exp(-pow(delta,2)/2.0)/pow(wavelength,2)*1e7/sqrt(2*M_PI);
+    return FINE_STRUCTURE_CONSTANT*qe*exp(-pow(delta,2)/2.0)/pow(wavelength,2)*1e7/sqrt(2*M_PI)/beta_sin_theta_theta0;
 }
 
 static double prob_scatter2(double wavelength, void *params)
@@ -194,10 +194,10 @@ void init_interpolation(void)
 double get_probability(double beta, double cos_theta, double sin_theta, double theta0)
 {
     /* Make sure theta0 is less than MAX_THETA0, otherwise it's possible that
-     * gsl_spline2d_eval() will quit. */
+     * interp2d() will quit. */
     if (theta0 > MAX_THETA0) theta0 = MAX_THETA0;
 
-    return interp2d(beta*cos_theta, beta*sin_theta*theta0, x, y, z, nx, ny)/(theta0*sin_theta);
+    return beta*interp2d(beta*cos_theta, beta*sin_theta*theta0, x, y, z, nx, ny);
 }
 
 double get_probability2(double beta)