Add LoopTools

* Add LoopTools v2.16.
   - c.f. https://feynarts.de/looptools/
* Looptools currently only supports static linking, so following CFEP-18,
  create 'looptools-static' output.
   - c.f. https://github.com/conda-forge/cfep/blob/main/cfep-18.md

recipes/looptools/examples/example01.cpp

@@ -0,0 +1,29 @@
+#include <stdio.h>
+#include "clooptools.h"
+
+#define MH2 (126.*126.)
+#define MZ2 (91.188*91.188)
+#define MW2 (80.4*80.4)
+#define Alfa (1./137.0359895)
+#define pi 3.14159265358979
+
+#define SW2 (1. - MW2/MZ2)
+
+static ComplexType SigmaH(double k2) {
+  return Alfa/(32*pi*SW2*MW2)*
+    ( 3*MH2*A0(MH2) + 9*MH2*MH2*B0(k2, MH2, MH2)
+    + 2*(MH2*MH2 - 4*MW2*(k2 - 3*MW2))*B0(k2, MW2, MW2)
+    + 2*(6*MW2 + MH2)*A0(MW2) - 24*MW2*MW2
+    + (MH2*MH2 - 4*MZ2*(k2 - 3*MZ2))*B0(k2, MZ2, MZ2)
+    + (6*MZ2 + MH2)*A0(MZ2) - 12*MZ2*MZ2 );
+}
+
+int main() {
+  RealType s;
+  ltini();
+  for( s = 100; s <= 1000; s += 50 ) {
+    ComplexType sig = SigmaH(s);
+    printf("%g\t%g%+gi\n", s, Re(sig), Im(sig));
+  }
+  ltexi();
+}

recipes/looptools/meta.yaml

@@ -0,0 +1,83 @@
+{% set name = "looptools" %}
+{% set version = "2.16" %}
+
+package:
+  name: {{ name }}
+  version: {{ version }}
+
+source:
+  url: https://feynarts.de/looptools/LoopTools-{{ version }}.tar.gz
+  sha256: 4113467575db3a14405d62d9e516b3b90410b73ea8d20c8eb8d70a30fc5cc9cb
+
+build:
+  number: 0
+
+outputs:
+  - name: {{ name }}-static
+
+    build:
+      skip: true  # [win]
+      run_exports:
+        - {{ pin_subpackage('looptools-static', max_pin='x.x') }}
+      ignore_run_exports_from:
+        - {{ compiler('cxx') }}
+      script:
+        # FIXME: Avoid error from trying to create directories that exist
+        - sed -i 's/mkdir /mkdir -p /g' makefile.in
+        - ./configure --help
+        # FIXME: Author has disabled builds with dynamic linking
+        # c.f. https://github.com/hep-packaging-coordination/packaging-hep-simulation-stack/issues/4#issuecomment-2489198926
+        # - ./configure --prefix=$PREFIX --dynamic --64 $CXXFLAGS
+        - ./configure --prefix=$PREFIX --64 $CXXFLAGS
+        - make
+        - make install
+        # conda just uses $PREFIX/lib
+        - mv $PREFIX/lib64/libooptools.a $PREFIX/lib/libooptools.a  # [linux]
+        - rm -rf build
+
+    requirements:
+      build:
+        - {{ stdlib('c') }}
+        - {{ compiler('cxx') }}
+        - {{ compiler('fortran') }}
+        - make
+        - sed
+        - gawk
+
+    test:
+      files:
+        - examples/
+      requires:
+        - {{ compiler('cxx') }}
+        - gfortran
+      commands:
+        - test ! -f $PREFIX/lib64/libooptools.a  # [linux]
+        - test -f $PREFIX/lib/libooptools.a
+        - test -f $PREFIX/include/looptools.h
+        - test -f $PREFIX/include/clooptools.h
+        - test -f $PREFIX/bin/lt
+        - test -f $PREFIX/bin/fcc
+        - test -f $PREFIX/bin/f++
+
+        - fcc --help
+        - f++ --help
+
+        - cd examples
+        - $CXX example01.cpp -o example01 $CXXFLAGS $LDFLAGS -looptools -lgfortran
+        - ./example01
+
+about:
+  home: https://feynarts.de/looptools/
+  summary: 'LoopTools: A package for evaluation of scalar and tensor one-loop integrals'
+  description: |
+    LoopTools is a package for evaluation of scalar and tensor one-loop integrals
+    based on the FF package by G.J. van Oldenborgh. It features an easy Fortran,
+    C++, and Mathematica interface to the scalar one-loop functions of FF and
+    in addition provides the 2-, 3-, and 4-point tensor coefficient functions.
+  license: GPL-3.0-only
+  license_family: GPL
+  license_file: COPYING
+
+extra:
+  recipe-maintainers:
+    - matthewfeickert