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MathGroup Archive 1990

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Does anyone have an apparent fix for this mathematica problem?

  • To: mathgroup at yoda.ncsa.uiuc.edu
  • Subject: Does anyone have an apparent fix for this mathematica problem?
  • From: uunet!oregon.uoregon.edu!JOE
  • Date: Thu, 7 Jun 90 09:10 PDT

Has anyone else heard of the problem my users describe below? Is a patch
available to make Mathematica on the NeXT yield the same results as 
Mathematica on the Mac?

If you've any queries Fred needs to see or respond to, please CC: him directly
since he's not on the list right now.

Thanks,

Joe St Sauver (JOE at OREGON.UOREGON.EDU or JOE at OREGON)
Statistical Programmer and Consultant
University of Oregon Computing Center

>From:	OREGON::OLNESS       "Fredrick Olness (503) 346-5206 OLNESS at OREGON"  
>To:	OREGON::JOE
>
>Joe,
>
> .... One of Bob Zimmerman's students
>found what appers to be a bug in Mathematica on the Next.
>(Yes, I did  not believe it until I tried it myself.)
>
>I attach two examples of the problem below. 
>(For reference, the Mac gave the correct answer,
>so it is not a subtle error pertaining to branch cuts or 
>anything.)  I think he was going to try it on a different Next 
>machine for comparison.
>
>Thanks,
>
>Fred.
>
>--- example one --
>1% math
>Mathematica 1.2 (August 30, 1989) [With pre-loaded data]
>by S. Wolfram, D. Grayson, R. Maeder, H. Cejtin,
>   S. Omohundro, D. Ballman and J. Keiper
>with I. Rivin and D. Withoff
>Copyright 1988,1989 Wolfram Research Inc.
>
>In[1]:= InputForm[(b*c*(a + d - (a^2 + 4*b*c - 2*a*d + d^2)^(1/2))^3)/
>           (4*(a - d + (a^2 + 4*b*c - 2*a*d + d^2)^(1/2))*
>               (a^2 + 4*b*c - 2*a*d + d^2)^(1/2)) -
>        (b*c*(a +                 d + (a^2 + 4*b*c - 2*a*d + d^2)^(1/2))^3)/
>           (4*(a - d                 - (a^2 + 4*b*c - 2*a*d + d^2)^(1/2))*
>               (a^2 + 4*b        *c - 2*a*d + d^2)^(1/2))]
>
>Out[1]//InputForm=
>  (b*c*(a + d - (a^2 + 4*b*c - 2*a*d + d^2)^(1/2))^3)/
>    (4*(a^2 + 4*b*c - 2*a*d + d^2)^(1/2)*
>      (a - d + (a^2 + 4*b*c - 2*a*d + d^2)^(1/2))) -
>   (b*c*(a + d + (a^2 + 4*b*c - 2*a*d + d^2)^(1/2))^3)/
>    (4*(a^2 + 4*b*c - 2*a*d + d^2)^(1/2)*
>      (a - d - (a^2 + 4*b*c - 2*a*d + d^2)^(1/2)))
>
>In[2]:= rule={a->1,b->2,c->3,d->4}
>
>Out[2]= {a -> 1, b -> 2, c -> 3, d -> 4}
>
>In[3]:= N[res//.rule]
>
>Out[3]= res
>
>In[4]:= res=%1;
>
>In[5]:= N[res//.rule]
>
>Out[5]= 37.
>
>In[6]:= N[Together[Expand[res]]//.rule]
>
>Out[6]= 47.2208
>
>In[7]:= N[Simplify[res]//.rule]
>
>Out[7]= 47.2208
>
>-- example two follows --
>
>1 % math
>Mathematica 1.2 (August 30, 1989) [With pre-loaded data]
>by S. Wolfram, D. Grayson, R. Maeder, H. Cejtin,
>   S. Omohundro, D. Ballman and J. Keiper
>with I. Rivin and D. Withoff
>Copyright 1988,1989 Wolfram Research Inc.
>
>In[1]:= InputForm[(b*c*(a + d - (a^2 - 2*a*c + 4*b*c + d^2)^(1/2))^3)/
>           (4*(a - d + (a^2 - 2*a*c + 4*b*c + d^2)^(1/2))*
>               (a^2 - 2*a*c + 4*b*c + d^2)^(1/2)) -
>        (b*c*(a + d + (a^2 - 2*a*c + 4*b*c + d^2)^(1/2))^3)/
>           (4*(a - d - (a^2 - 2*a*c + 4*b*c + d^2)^(1/2))*
>               (a^2 - 2*a        *c + 4*b*c + d^2)^(1/2))]
>
>
>Out[1]//InputForm=
>  (b*c*(a + d - (a^2 - 2*a*c + 4*b*c + d^2)^(1/2))^3)/
>    (4*(a^2 - 2*a*c + 4*b*c + d^2)^(1/2)*
>      (a - d + (a^2 - 2*a*c + 4*b*c + d^2)^(1/2))) -
>   (b*c*(a + d + (a^2 - 2*a*c + 4*b*c + d^2)^(1/2))^3)/
>    (4*(a^2 - 2*a*c + 4*b*c + d^2)^(1/2)*
>      (a - d - (a^2 - 2*a*c + 4*b*c + d^2)^(1/2)))
>
>In[2]:= res=%;
>
>In[3]:= rule={a->1,b->2,c->3,d->4}
>
>Out[3]= {a -> 1, b -> 2, c -> 3, d -> 4}
>
>In[4]:= N[res//.rule]
>
>Out[4]= 36.9231
>
>In[5]:= N[Together[Expand[res]]//.rule]
>
>Out[5]= 46.9906
>
>In[6]:= N[Simplify[res]//.rule]
>
>Out[6]= 46.9906


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