2007.03592.x.</p>
<p><strong>Notes</strong></p>
<p>In here I have made the Chebyshev polinomials unitless, 
meaning that the associated parameters ALL have units 
of the PSD and need to be normalized by 1/W for lpha_1, 
1/W**2 for lpha_2, etc.</p>
<p><strong>Modified</strong></p>
<p>Nov 2021 (German A Prieto)</p>
<p>Major adjustment in the inverse problem steps. 
Now, the constant term is first inverted for, 
and then the 1st and 2nd derivative so that we 
obtain an independent 2nd derivative.</p>
<p>June