From e64d353865337d48ba5123be583a71e08983f7af Mon Sep 17 00:00:00 2001
From: Philip Eisenlohr <eisenlohr@egr.msu.edu>
Date: Wed, 24 Jun 2020 18:37:33 -0400
Subject: [PATCH] condensed scale_to_coprime; added test of scale_to_coprime

---
 python/damask/util.py     | 11 +++++++----
 python/tests/test_util.py | 23 ++++++++++++++++++++++-
 2 files changed, 29 insertions(+), 5 deletions(-)

diff --git a/python/damask/util.py b/python/damask/util.py
index 471a5069b..cf99dc1b9 100644
--- a/python/damask/util.py
+++ b/python/damask/util.py
@@ -166,10 +166,13 @@ def scale_to_coprime(v):
         """Least common multiple."""
         return a * b // np.gcd(a, b)
 
-    denominators = [int(get_square_denominator(i)) for i in v]
-    s = reduce(lcm, denominators) ** 0.5
-    m = (np.array(v)*s).astype(np.int)
-    return m//reduce(np.gcd,m)
+    m = (np.array(v) * reduce(lcm, map(lambda x: int(get_square_denominator(x)),v)) ** 0.5).astype(np.int)
+    m = m//reduce(np.gcd,m)
+
+    if not np.allclose(v/m,v[0]/m[0]):
+        raise ValueError(f'Invalid result {m} for input {v}. Insufficient precision?')
+
+    return m
 
 
 ####################################################################################################
diff --git a/python/tests/test_util.py b/python/tests/test_util.py
index e67478d82..de6926e8c 100644
--- a/python/tests/test_util.py
+++ b/python/tests/test_util.py
@@ -1,11 +1,32 @@
+import pytest
+import numpy as np
 from damask import util
 
+
 class TestUtil:
 
     def test_execute_direct(self):
         out,err = util.execute('echo test')
         assert out=='test\n' and err==''
-    
+
     def test_execute_env(self):
         out,err = util.execute('sh -c "echo $test_for_execute"',env={'test_for_execute':'test'})
         assert out=='test\n' and err==''
+
+    def test_croak(self):
+        util.croak('Burp!')
+
+    @pytest.mark.parametrize('input,output',
+                            [
+                            ([0.5,0.5],[1,1]),
+                            ([1./2.,1./3.],[3,2]),
+                            ([2./3.,1./2.,1./3.],[4,3,2]),
+                            ])
+
+    def test_scale2coprime(self,input,output):
+        assert np.allclose(util.scale_to_coprime(np.array(input)),
+                                                 np.array(output).astype(int))
+
+    def test_lackofprecision(self):
+        with pytest.raises(ValueError):
+            util.scale_to_coprime(np.array([0.66,0.5,0.33]))