Photon ratios
Convenience functions for calculation of photon ratios between pairs of regions of the UV and VIS light spectrum.

R_FR()

Calculate R:FR photon ratio from spectral irradiance. 
B_G()

Calculate B:G photon ratio from spectral irradiance. 
UVB_UV()

Calculate UVB:UV photon ratio from spectral irradiance. 
UVA_UV()

Calculate UVA:UV photon ratio from spectral irradiance. 
UV_PAR()

Calculate UV:PAR photon ratio from spectral irradiance. 
UVB_PAR()

Calculate UVB:PAR photon ratio from spectral irradiance. 
UVA_PAR()

Calculate UVA:PAR photon ratio from spectral irradiance. 