Removed unnecessary computations, now at 16000x faster, H/T mikeblas.

test/test-martinheinz.py

@@ -19,6 +19,7 @@ def exp(x):
 
 print("Original:")
 
+
 d1_orig = exp(Decimal(150))
 d2_orig = exp(Decimal(400))
 d3_orig = exp(Decimal(3000))
@@ -34,8 +35,8 @@ def exp_opt(x):
     while s != lasts:
         lasts = s
         i += 1
-        fact *= i
-        num *= x
+        # was: fact *= i
+        # was: num *= x
         nf *= (x / i) ### update nf to be num / fact
         s += nf ### was: s += num / fact
     getcontext().prec -= 2
@@ -59,3 +60,5 @@ def exp_opt(x):
 assert d2_orig == d2_opt
 assert d3_orig == d3_opt
 
+print("All equivalent? ", d1_orig == d1_opt and d2_orig == d2_opt and d3_orig == d3_opt)
+