Re: MachinePrecission and FPU

*To*: mathgroup at smc.vnet.net*Subject*: [mg81292] Re: MachinePrecission and FPU*From*: Jean-Marc Gulliet <jeanmarc.gulliet at gmail.com>*Date*: Tue, 18 Sep 2007 05:55:15 -0400 (EDT)*Organization*: The Open University, Milton Keynes, UK*References*: <fcnl4n$s65$1@smc.vnet.net>

dh wrote: > I could trace down a discrepancy between a C program and Mathematica to the > > following. Try to compute 0.03/0.006 and you get 4.9999999.. as neither > > 0.03 nor 0.006 can be represented accurately, this is not amazing. On my system (Intel Pentium 4 HT 2.6 MHz), I get consistently 5.0 with version 6.0.1 and 5.2. In[1]:= 0.03/0.006 Out[1]= 5. In[2]:= $Version Out[2]= "6.0 for Microsoft Windows (32-bit) (June 19, 2007)" In[1]:= 0.03/0.006 Out[1]= 5. In[2]:= $Version Out[2]= 5.2 for Microsoft Windows (June 20, 2005) > However, the same calculated with C and C++ on PC's gives 5.0000.. /* Very crude C program */ #include <stdio.h> int main(void) { printf("The value of 0.03/0.006 is %f\n", 0.03/0.006); return 0; } which returns after compilation The value of 0.03/0.006 is 5.000000 > Now, WHY? Could that be hardware dependent? You did not mention either the version of Mathematica your used or the cpu. <snip> Regards, -- Jean-Marc