# FINDEB: function to calculate eb matrix

# function takes two arguments:
#   abs is sample x wavelength matrix of absorbances
#   conc is sample x analyte matrix of concentration
# function returns one result
#   eb is analyte x wavelength matrix of predicted eb values
# as.matrix assures dataframe is treated as matrix

findeb = function(abs, conc){
	abs.m = as.matrix(abs)
	conc.m = as.matrix(conc)
	ct = t(conc.m)
	ctc = ct %*% conc.m
	invctc = solve(ctc)
	eb = invctc %*% ct %*% abs.m
	output = eb
	invisible(output)
}

# FINDCONC: function to calculate concentration matrix

# function takes two arguments:
#   abs is sample x wavelength matrix of absorbances
#   eb is analyte x wavelength matrix of eb values
# function returns one result
#   pred.conc is sample x analyte matrix of predicted concentrations
# as.matrix assures dataframe is treated as matrix
# round trucates all values to four decimal place

findconc = function(abs, eb){
	abs.m = as.matrix(abs)
	eb.m = as.matrix(eb)
	ebt = t(eb.m)
	ebebt = eb %*% ebt
	invebebt = solve(ebebt)
	pred_conc = round(abs.m %*% ebt %*% invebebt, digits = 5)
	output = pred_conc
	invisible(output)
}