Add a script to compute powers of 10

support/compute-powers.py

@@ -0,0 +1,16 @@
+#!/usr/bin/env python
+# Compute 10 ** exp with exp in the range [min_exponent, max_exponent] and print
+# normalized (with most-significant bit equal to 1) significands in hexadecimal.
+
+from __future__ import print_function
+
+min_exponent = -348
+max_exponent = 340
+step = 8
+significand_size = 64
+for exp in range(min_exponent, max_exponent + 1, step):
+    n = 10 ** exp if exp >= 0 else 2 ** 2000 / 10 ** -exp
+    k = significand_size + 1
+    # Convert to binary and round.
+    n = (int('{:0<{}b}'.format(n, k)[:k], 2) + 1) / 2
+    print('{:0<#16x}ull'.format(n))