Tried implementing getting the chi2 gradient, using target_function.chi2.dchi2().
The output seem equal.
task #7822(https://gna.org/task/index.php?7822): Implement user function to estimate R2eff and associated errors for exponential curve fitting.
Authored by: tlinnet 2014-08-29
Parent: [r25432]
Child: [r25434]
