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Problem with Expand and Modulus in Mathematica 9?
Posted:
Dec 28, 2012 5:33 AM


Can someone confirm that the following code gives different results for r1 for different versions of Mathematica and different operating systems. Or is this just an issue of my installation?
BEGIN CODE m = 2147483629 q = 285170499 q1 = 1/q q2 = PowerMod[q,1,m] Mod[q*q2, m] p1 = 527660967 + 978421595*n p2 = 1999783961 + 1587123368*n + 1965760814*n^2 r1 = Expand[q1*p1*p2,Modulus>m] r2 = Expand[q2*p1*p2,Modulus>m] s1 = Expand[Expand[q1*p1*p2],Modulus>m] s2 = Expand[Expand[q2*p1*p2],Modulus>m] END CODE
Value of r1 Mathematica 8 1808010833 + 1914426603*n + 640234431*n^2 + 1087084730*n^3
Mathematica 9 (64bit Debian 6.0) 1651432217 + 309632549*n + 188919829*n^2 + 1597920481*n^3
Mathematica 9 (32bit Debian 6.0, 64bit CPU) 1823075307 + 33175446*n + 2081129601*n^2 + 580053941*n^3
The values of r2, s1, s2 agree with that of r1 as computed in Mathematica 8.
Ralf



