An additional layer of equations to simplify the relaxation equations, gradients, and hessians.
The R1 and R2 equations are left alone, while the NOE is decomposed into the cross relaxation rate equation and the R1 equation.
The relaxation gradients
~~~~~~~~~~~~~~~~~~~~~~~~
Data structure:  self.data.dri
Dimension:  2D, (parameters, relaxation data)
Type:  Numeric array, Float64
Dependencies:  self.data.ri_prime, self.data.dri_prime
Required by:  self.data.dchi2, self.data.d2chi2
Formulae
~~~~~~~~
         dR1()       dR1'()
        -------  =  -------
        dthetaj     dthetaj
         dR2()       dR2'()
        -------  =  -------
        dthetaj     dthetaj
         dNOE()     gH      1      /        dsigma_noe()                    dR1()  \ 
        -------  =  -- . ------- . | R1() . ------------  -  sigma_noe() . ------- |
        dthetaj     gN   R1()**2   \          dthetaj                      dthetaj /
  
   
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