int solar_angles(float J_day, float gmt, float lat, float lon, float *zenith, float *azimuth);
int conv_spline(int n_wl, float *wl, int n_irrad, 
	float **m_irrad, float *conv);
int conv_tri(float bw, int n_wl, float *wl, int n_irrad, 
	float **m_irrad, float *conv);
int conv_rect(float bw, int n_wl, float *wl, int n_irrad, 
	float **m_irrad, float *conv);
int conv_gauss(float bw, int n_wl, float *wl, float cutoff, 
	int n_irrad, float **m_irrad, float *conv);
int conv_filt(float **filter, float *wl, 
	int n_filt_row, int n_filt_col, int n_wl, int n_irrad, 
	float **m_irrad, float *conv);
int store_header(FILE *fp_out, char time_file[], int conv_fnc, float bw, 
	float min_wl, float max_wl, float inc_wl, int n_time, 
	int day[], float time[], float zenith[], float azimuth[]);