Avoid an overflow

CalebBell · May 15, 2021 · 5ba59e1 · 5ba59e1
1 parent 824eb8f
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Showing 2 changed files with 13 additions and 1 deletion.
diff --git a/chemicals/dippr.py b/chemicals/dippr.py
@@ -570,7 +570,14 @@ def EQ106(T, Tc, A, B, C=0.0, D=0.0, E=0.0, order=0):
     '''
     if order == 0:
         Tr = T/Tc
-        return A*(1. - Tr)**(B + Tr*(C + Tr*(D + E*Tr)))
+        tau = (1.0 - Tr)
+        power = (B + Tr*(C + Tr*(D + E*Tr)))
+        try:
+            return A*tau**power
+        except:
+            # TODO: after more testing with regression, maybe return a more
+            # precise value or allow A to impact the result
+            return 1e300
     elif order == 1:
         x0 = 1.0/Tc
         x1 = T*x0

diff --git a/tests/test_dippr.py b/tests/test_dippr.py
@@ -91,6 +91,11 @@ def test_EQ106_more():
     d3_numerical = derivative(lambda T: EQ106(T, 647.096, 0.17766, 2.567, -3.3377, 1.9699, order=2), 300.0, dx=1e-4)
     assert_close(d3_analytical, -5.524739890945817e-09, rtol=1e-13)
     assert_close(d3_analytical, d3_numerical, rtol=1e-8)
+
+    # check that this regression set of points does not produce an error
+    overflow_kwargs = {'T': 304.747, 'Tc': 405.4, 'A': 56.743647419038744, 'B': -75.36242555958763,
+                   'C': -141.1028969227863, 'D': -254.76349199392695, 'E': -442.5916844036474, 'order': 0}
+    EQ106(**overflow_kwargs)
 
 
 def test_EQ101_more():