CPU time for Solve under v.2.0 and 2.1

• To: mathgroup at yoda.physics.unc.edu
• Subject: CPU time for Solve under v.2.0 and 2.1
• From: yoda at ele.crl.melco.co.jp
• Date: Fri, 13 Nov 92 15:40:53 JST

```Dear mma users,

here's an example of strange v.2.1 behavior when I try to solve
a matrix equation using the Solve command on my Mac IIci + a Tokamac 68040
board.

As we see, the same program below gives very different CPU time !!!
A bad part is that the v.2.1 gives 5 times longer CPU time !!!!!

Kiyoshi Yoda

----- v.2.0  -------

Share[]

i0=1;

n=8;

va=Array[v,n];

Do[v[i]=0,{i,n-2,n}];

kktotal=Array[d,{n,n}];

Do[d[j+i,j]=d[j,j+i],{j,n},{i,n}]

Do[kktotal[[i]]=Table[0,{n}],{i,n-2,n}]

Timing[Solve[kktotal.va==ReplacePart[Table[0,{n}],i0,1],
{v[1],v[2],v[3],v[4],v[5]}]][[1]]

5.08333 Second
---------------------------------------------------------

----v. 2.1 ---------

Share[]
80960

i0=1;

n=8;

va=Array[v,n];

Do[v[i]=0,{i,n-2,n}];

kktotal=Array[d,{n,n}];

Do[d[j+i,j]=d[j,j+i],{j,n},{i,n}]

Do[kktotal[[i]]=Table[0,{n}],{i,n-2,n}]

Timing[Solve[kktotal.va==ReplacePart[Table[0,{n}],i0,1],
{v[1],v[2],v[3],v[4],v[5]}]][[1]]

27.2333 Second
----------------------------------------------------------

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*   Kiyoshi Yoda, Ph.D                *
*                                     *
*   Mitsubishi Electric Corporation   *
*   Central Research Laboratory       *
*   8-1-1 Tsukaguchi-Hommachi         *
*   Amagasaki, 661 Japan              *
*                                     *
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```

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