minimum GSL version requirement

[bastistician]

Both

gsl/DESCRIPTION

Line 8 in d28d8fe

SystemRequirements: Gnu Scientific Library version >= 2.1

and

gsl/configure.ac

Line 50 in d28d8fe

AC_MSG_ERROR([Need GSL version >= 1.16])

seem to be outdated.

Ubuntu 18.04 ships GSL 2.4 but configuration of the newly released gsl 2.1-7 fails with

configure: error: Need GSL version >= 1.16
ERROR: configuration failed for package 'gsl'

[wviechtb]

Commit 3e826bb updated the requirement to 2.5 (which ships with 20.04) but that error message wasn't updated (in configure and configure.ac).

[RobinHankin]

thanks for this, will fix shortly

[bastistician]

Thanks. The system requirement stated in the DESCRIPTION would also need an update.

[aitap]

Currently, the ./configure test checks for any minor version of 5 and above, not >= 2.5:

$ cat version.c
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char ** argv) {
	int major, minor;
	if (argc != 2) return -1;
	if (sscanf(argv[1], "%d.%d", &major, &minor) != 2) return -1;
	exit(minor < 5);
	exit(major < 2);
}
$ cc -o version version.c
$ ./version 1.5 && echo test passed
test passed
$ ./version 3.0 || echo test failed
test failed

This happens because the first call to exit terminates the process, ignoring the value of major.
Comparing versions is hard [1, 2]. I think that a correct way to compare versions would be something along the lines of:

if (major < 2) return 1;
if (major > 2) return 0;
if (minor < 5) return 1;
return 0;