sci-libs/gsl: fudge tolerance to fix a flaky test

Add a non-upstream patch to embiggen this tolerance.

Closes: https://bugs.gentoo.org/664936
Signed-off-by: Michael Orlitzky <mjo@gentoo.org>

2 files changed, 109 insertions, 0 deletions

diff --git a/sci-libs/gsl/files/gsl-2.7.1-test-tolerance.patch b/sci-libs/gsl/files/gsl-2.7.1-test-tolerance.patch
new file mode 100644
index 000000000000..8ddce4388e90
--- /dev/null
+++ b/sci-libs/gsl/files/gsl-2.7.1-test-tolerance.patch
@@ -0,0 +1,47 @@
+From 8306771281f9b2883c5200ee241b0c0767bfe1b4 Mon Sep 17 00:00:00 2001
+From: Michael Orlitzky <michael@orlitzky.com>
+Date: Sun, 30 Jun 2024 19:45:45 -0400
+Subject: [PATCH 1/1] eigen/test.c: loosen tolerance in eigenvalue norm tests
+
+One test for the (unit) norm of a random hermitian matrix's
+eigenvalues is victim to tolerance issues, e.g.
+
+  FAIL: herm random, normalized(1), unsorted (0.999999999999999112
+  observed vs 1 expected) [117761]
+
+The tolerance used is N*GSL_DBL_EPSILON, where N is the size of the
+matrix. On my machine, the actual error is four times GSL_DBL_EPSILON,
+which means that the tolernace is close but not quite right. Despite
+having done a PhD in numerical analysis, I am choosing to fix this
+with a shotgun:
+
+  * By a factor of 10
+  * Then also by a factor of N
+
+That's still extremely close, and hopefully will sweep the problem
+under the rug whether it's off by a constant or off by a function
+of N.
+
+Bug: https://bugs.gentoo.org/664936
+Bug: https://git.adelielinux.org/adelie/packages/-/issues/504
+Bug: https://savannah.gnu.org/bugs/?56843
+---
+ eigen/test.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/eigen/test.c b/eigen/test.c
+index b0bdcc7..2681721 100644
+--- a/eigen/test.c
++++ b/eigen/test.c
+@@ -506,7 +506,7 @@ test_eigen_herm_results (const gsl_matrix_complex * A,
+     {
+       gsl_vector_complex_const_view vi = gsl_matrix_complex_const_column(evec, i);
+       double nrm_v = gsl_blas_dznrm2(&vi.vector);
+-      gsl_test_rel (nrm_v, 1.0, N * GSL_DBL_EPSILON, "%s, normalized(%d), %s", 
++      gsl_test_rel (nrm_v, 1.0, N*N * 10.0 * GSL_DBL_EPSILON, "%s, normalized(%d), %s", 
+                     desc, i, desc2);
+     }
+ 
+-- 
+2.44.2
+
diff --git a/sci-libs/gsl/gsl-2.7.1-r3.ebuild b/sci-libs/gsl/gsl-2.7.1-r3.ebuild
new file mode 100644
index 000000000000..81205249e873
--- /dev/null
+++ b/sci-libs/gsl/gsl-2.7.1-r3.ebuild
@@ -0,0 +1,62 @@
+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit autotools flag-o-matic toolchain-funcs
+
+DESCRIPTION="The GNU Scientific Library"
+HOMEPAGE="https://www.gnu.org/software/gsl/"
+SRC_URI="mirror://gnu/${PN}/${P}.tar.gz
+	https://dev.gentoo.org/~sam/distfiles/${CATEGORY}/${PN}/${PN}-2.7-cblas.patch.bz2"
+
+LICENSE="GPL-3+"
+# Usually 0/${PV} but check
+SLOT="0/27"
+KEYWORDS="~alpha ~amd64 ~arm ~arm64 ~hppa ~ia64 ~loong ~mips ~ppc ~ppc64 ~riscv ~s390 ~sparc ~x86 ~amd64-linux ~x86-linux"
+IUSE="cblas-external +deprecated static-libs"
+
+RDEPEND="cblas-external? ( virtual/cblas:= )"
+DEPEND="${RDEPEND}"
+BDEPEND="virtual/pkgconfig"
+
+PATCHES=(
+	"${WORKDIR}"/${PN}-2.7-cblas.patch
+	"${FILESDIR}"/${PN}-2.7.1-configure-clang16.patch
+	"${FILESDIR}"/${PN}-2.7.1-test-tolerance.patch
+)
+
+src_prepare() {
+	default
+
+	if use deprecated; then
+		sed -i -e "/GSL_DISABLE_DEPRECATED/,+2d" configure.ac || die
+	fi
+
+	eautoreconf
+}
+
+src_configure() {
+	filter-flags -ffast-math
+
+	if use cblas-external; then
+		export CBLAS_LIBS="$($(tc-getPKG_CONFIG) --libs cblas)"
+		export CBLAS_CFLAGS="$($(tc-getPKG_CONFIG) --cflags cblas)"
+	fi
+
+	econf \
+		--enable-shared \
+		$(use_with cblas-external) \
+		$(use_enable static-libs static)
+}
+
+src_test() {
+	local MAKEOPTS="${MAKEOPTS} -j1"
+	default
+}
+
+src_install() {
+	default
+
+	find "${ED}" -name '*.la' -delete || die
+}