> As you can see the outputs for the z data match the input exactly?
That is NOT true. I just tried the following to convert the z-score to r:
3dcalc -a Grp_t_fa_LMFG_312727+tlrc'[0]' -expr '(exp(2*a)-1)/(exp(2*a)+1)' -prefix test
and the values in test+tlrc are NOT exactly the same as Grp_t_fa_LMFG_312727+tlrc'[0]'. They are indeed vary close simply because all the values in Grp_t_fa_LMFG_312727+tlrc'[0]' fall into interval (-0.392432, 0.482834), and the transformation does not change much in that range, but again they are not exactly the same.