Function Description
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	Name: SUM_LOREN (Sum of two Lorentzians) 
	Function: f(x) = Mo*(loren1 + F*loren2) 
	Parameters: Vo(1) T1(1) Vo(2) T1(2) Mo F

Notes
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Vo(1), Vo(2) are the maximum values of the Lorentzians.
T1(1), T1(2) are measures of line width of the Lorentzians.
F measures relative intensity of Lorentzian 1 to Lorentzian 2.
Mo is a scaling factor.


C-code for the function
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b = 4.0 * PI * PI;
c = a[1] / (1 + b * (x-a[0])*(x-a[0]) * (a[1]*a[1]));
d = a[3] / (1 + b * (x-a[2])*(x-a[2]) * (a[3]*a[3]));
answer = -a[4] * (c - a[5]*d);