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MathGroup Archive 1998

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A simple bug..




I seem to have come across this  simple and reproducible bug :

The error is in the last line of this post (the others are simply
reproducing my previous steps) where "h" is not being replaced.....

Mathematica 3.0 for NEXTSTEP Intel
Copyright 1988-97 Wolfram Research, Inc.
 -- Motif graphics initialized -- 

In[1]:= phi={
                1 - 3 (x/h)^2 + 2 (x/h)^3,
                -x(1-x/h)^2,
                3(x/h)^2 - 2 (x/h)^3,
                -x( (x/h)^2 - (x/h))}                                

                2      3                    2      3               2
             3 x    2 x            x 2   3 x    2 x          x    x
Out[1]= {1 - ---- + ----, -(x (1 - -) ), ---- - ----, -(x (-(-) + --))}
               2      3            h       2      3          h     2
              h      h                    h      h                h

In[2]:= k1[i_,j_]:=
        Integrate[
                ( e in  
                                         D[phi[[i]],{x,2}]  
D[phi[[j]],{x,2}] 
                ), {x,0,h}]                         Syntax::newl: The
newline character after "             ( e in  "
     is understood as a multiplication operator.

        

In[3]:= k1matrix=Table[k1[i,j], {i,4},{j,4}]

          12 e in  -6 e in  -12 e in  -6 e in
Out[3]= {{-------, -------, --------, -------}, 
             3        2         3        2
            h        h         h        h
 
      -6 e in  4 e in  6 e in  2 e in    -12 e in  6 e in  12 e in  6 e in
>    {-------, ------, ------, ------}, {--------, ------, -------,  
------}, 
         2       h        2      h           3        2       3        2
        h                h                  h        h       h        h
 
      -6 e in  2 e in  6 e in  4 e in
>    {-------, ------, ------, ------}}
         2       h        2      h
        h                h

In[4]:= k1matrix=Table[k1[i,j], {i,4},{j,4}] /. h->6    

          e in  -(e in)  -(e in)  -(e in)    -(e in)  2 e in  e in  e in
Out[4]= {{----, -------, -------, -------}, {-------, ------, ----, ----}, 
           18      6       18        6          6       3      6     3
 
      -(e in)  e in  e in  e in    -(e in)  e in  e in  2 e in
>    {-------, ----, ----, ----}, {-------, ----, ----, ------}}
        18      6     18    6         6      3     6      3

In[5]:= k1matrix=Table[k1[i,j], {i,4},{j,4}] /. e*in -> 10^6

          12000000  -6000000  -12000000  -6000000
Out[5]= {{--------, --------, ---------, --------}, 
              3         2         3          2
             h         h         h          h
 
      -6000000  4000000  6000000  2000000
>    {--------, -------, -------, -------}, 
          2        h        2        h
         h                 h
 
      -12000000  6000000  12000000  6000000
>    {---------, -------, --------, -------}, 
          3         2         3        2
         h         h         h        h
 
      -6000000  2000000  6000000  4000000
>    {--------, -------, -------, -------}}
          2        h        2        h
         h                 h

In[6]:= k1matrix=Table[k1[i,j], {i,4},{j,4}] /. {h->6, e*in ->10^6}

          12000000  -6000000  -12000000  -6000000
Out[6]= {{--------, --------, ---------, --------}, 
              3         2         3          2
             h         h         h          h
 
      -6000000  4000000  6000000  2000000
>    {--------, -------, -------, -------}, 
          2        h        2        h
         h                 h
 
      -12000000  6000000  12000000  6000000
>    {---------, -------, --------, -------}, 
          3         2         3        2
         h         h         h        h
 
      -6000000  2000000  6000000  4000000
>    {--------, -------, -------, -------}}
          2        h        2        h
         h                 h


In[7]:= 

--
Jagannatha Rao				E-mail:rao@uh.edu
Associate Professor
Department of Mechanical Engineering    Tel   :(713) 743-4535 University
of Houston                   Fax   :(713) 743-4503 Houston, TX
77204-4792




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