what is wrong here?
- To: mathgroup@smc.vnet.net
- Subject: [mg12103] what is wrong here?
- From: rao@supermod.egr.uh.edu (Dr. Jagannatha Rao)
- Date: Sat, 25 Apr 1998 01:30:34 -0400
- Organization: University of Houston
I am having a lot of difficulty in trying to use commands on a matrix as
follows:
matrix[[{i,j,k},{i,j,k}]] = matrix[[{i,j,k},{i,j,k}]] + some 3x3 matrix.
See the example below. When i,j,k areconsecutive indices, there seems
to be no problem. When the indices are, say {3,4,7,8}, the program
always crashes with a bus error.
----------------------------------------------------------
supermod 103$ math
Mathematica 3.0 for NEXTSTEP Intel
Copyright 1988-97 Wolfram Research, Inc.
-- Motif graphics initialized --
In[1]:= matrix = Table[a , {i,8},{j,8}]
Out[1]= {{a, a, a, a, a, a, a, a}, {a, a, a, a, a, a, a, a},
> {a, a, a, a, a, a, a, a}, {a, a, a, a, a, a, a, a},
> {a, a, a, a, a, a, a, a}, {a, a, a, a, a, a, a, a},
> {a, a, a, a, a, a, a, a}, {a, a, a, a, a, a, a, a}}
In[2]:= matrix[[{1,2,3,4},{1,2,3,4}]] //MatrixForm
Out[2]//MatrixForm= a a a a
a a a a
a a a a
a a a a
In[3]:= temp=Table[b, {i,4},{j,4}]
Out[3]= {{b, b, b, b}, {b, b, b, b}, {b, b, b, b}, {b, b, b, b}}
In[4]:= matrix[[{1,2,3,4},{1,2,3,4}]] = \ matrix[[{1,2,3,4},{1,2,3,4}]]
+ temp
Out[4]= {{a + b, a + b, a + b, a + b}, {a + b, a + b, a + b, a + b},
> {a + b, a + b, a + b, a + b}, {a + b, a + b, a + b, a + b}}
In[5]:= matrix //MatrixForm
Out[5]//MatrixForm=
> a + b a + b a + b a + b a a a a
a + b a + b a + b a + b a a a a
a + b a + b a + b a + b a a a a
a + b a + b a + b a + b a a a a
a a a a a a a a
a a a a a a a a
a a a a a a a a
a a a a a a a a
In[6]:= matrix = Table[a , {i,8},{j,8}]
Out[6]= {{a, a, a, a, a, a, a, a}, {a, a, a, a, a, a, a, a},
> {a, a, a, a, a, a, a, a}, {a, a, a, a, a, a, a, a},
> {a, a, a, a, a, a, a, a}, {a, a, a, a, a, a, a, a},
> {a, a, a, a, a, a, a, a}, {a, a, a, a, a, a, a, a}}
In[7]:= matrix[[{3,4,7,8},{3,4,7,8}]]= \ matrix[[{3,4,7,8},{3,4,7,8}]] +
temp Bus error
supermod 104$
--
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