make params more consistent

                        0.25        & maximum echo average deviation from $(up+down)/2$ \\

\hline

{\tt r.fqt\_min}        & % {\tt fqt\_min\_value}  &

                        0.10        & minimum value of F(Q,t)      \\ % replaces r.min\_amplitude \\

                        0.10        & minimum value of $F(Q,t)$. Applied when actually fitting is done, typically for resolution samples.\\

\hline

{\tt r.fqt\_maxsigma}   & % {\tt fqt\_max\_sigma} &

                        1.0         & maximum $\sigma_{F(Q,t)}/F(Q,t)$ ?? $\sigma^2$ \\ % eplaces r.max\_rel\_error

                        1.0         & maximum $\sigma_{F(Q,t)}/F(Q,t)$ \\

\hline

{\tt r.phase\_tol}      & %{\tt symmetry\_phase\_tolerance} &

                        $10^{-10}$  & echo phase fitting tolerance \\

% integer :: symmetry_phase_patch_size     % !> patch size for symmetry phase smoothing algorithm

\hline

{\tt r.postcoll\_qcat}  & % {\tt post\_collection\_qcatch} &

                        0.0         & catch band for post collecting q-values \\

                        0.0         & catch band for q-value automatic binning (post collection). Similar to {\tt tau iterate}, 0 means it is disabled.\\

\hline

{\tt r.max\_field\_var} & % {\tt max\_bfield\_variation}   &

                        $10^{-6}$   & maximum magnetic field variation in a scan   \\

we can write Eq. \ref{eq4p:1} in a more compact form:

\begin{equation}

\label{eq4p:1b}

I(\prime{\delta}-\delta_0) = b + a \; \exp(-\Psi^2) \; \cos(\Phi)

I(\delta^\prime-\delta_0) = b + a \; \exp(-\Psi^2) \; \cos(\Phi)

\end{equation}

or

\begin{equation}

\label{eq4p:1c}

I(\delta\prime-\delta_0) = b + \underbrace{a {\cal R}}_{a_x}\; 

I(\delta^\prime-\delta_0) = b + \underbrace{a {\cal R}}_{a_x}\; 

                \exp\left(-\frac{\Lambda^2}{\lambda_0^2} \Phi^2 \; A^2 \right) \; \cos(\Phi)

\end{equation}

with the resolution factor

 {\cal R} =  \eta \exp\left(-\frac{\Sigma^2}{\lambda_0^2} g^2 / A^2 \right)

\end{equation}

the echo amplitude is $a$, the average value $b$ and the field integral assymmetry $\delta_0$.

The scanning parameter is $\delta\prime$, $\Phi_0 = \delta_0 g \lambda_0 /A^2$,

The scanning parameter is $\delta^\prime$, $\Phi_0 = \delta_0 g \lambda_0 /A^2$,

$\eta$ a factor accounting for polarisation efficiency.

First of all the echo amplitude to be determined from the proper phase scan at the instrument is $a_x$.

The Gaussian wavelengt width $\Lambda$ relates to the common FWHM selector parameter (0.1$\dots$0.2)

                if(refpix%status .ne. PIXEL_OK ) cycle dtypd

                if(all ( [ refpix%average%value  > reduction_parameters%average_min_value,&

                           refpix%fqt%value  > reduction_parameters%fqt_min_value,&

                           refpix%fqt%sigma2 < reduction_parameters%fqt_max_sigma] )) then

                           sqrt(refpix%fqt%sigma2)/refpix%fqt%value < reduction_parameters%fqt_max_sigma] )) then

                   eshape_lams%nbin = [datpix%tbin_1, datpix%tbin_2]

                   call linextract(eshape, datpix, eshape_lams, datpix%delta_J_symm%value+dj, ssq)