[Help-gsl] Interpolation - moving from v 1.9 to 1.11

[Cathy Laporte]

Hi,

I am currently in the process of migrating from gsl-1.9 to gsl-1.11.  I
noticed that there was a change in the interpolation routines of the
library.  Namely, the interp_init routine now checks that the x values
of the data are sorted in increasing order.  This change has brought a
bug in my own code to my attention: occasionally, it tries to create an
interpolant with a small number of incorrectly ordered (but quite
similar) x values at one extreme of the range of my data.  Using
gsl-1.9, this bug was rather asymptomatic as the library did not issue
any error messages and most of my interpolation queries were probably
not in the dubious part of my x axis anyway.  Nonetheless, for the
purpose of understanding what sort of impact this bug may have had on
the output I previously obtained from my code, I would like to
understand how interpolant queries behaved with incorrectly ordered x
values in gsl-1.9.  Does anyone know?

Many thanks in advance,

Cathy Laporte