Complex I
- To: uiucuxc!yoda.ncsa.uiuc.edu!mathgroup
- Subject: Complex I
- From: Rod Frehlich <uiucuxc!terra.Colorado.EDU!rgf>
- Date: Wed, 14 Mar 90 15:17:25 MST
The strange convention of placing negative signs with the complex number I
produces errors with substitutions. For example, the following program
AppendTo[$Echo, "stdout"]
(* Error in Rules *)
a = I*x/f-I*x/g+z
a = a /.{x_/f-x_/g -> x/h}
(* Error disappears if I is replaced by a variable *)
b = v*x/f-v*x/g+z
b = b /.{x_/f-x_/g -> x/h}
results in
Mathematica (sun3.68881) 1.2 (November 6, 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.
-- Terminal graphics initialized --
In[1]:=
Out[1]= {stdout}
In[2]:= (* Error in Rules *)
In[3]:= a = I*x/f-I*x/g+z
I x -I x
Out[3]= --- + ---- + z
f g
In[4]:= a = a /.{x_/f-x_/g -> x/h}
I x -I x
Out[4]= --- + ---- + z
f g
In[5]:= (* Error disappears if I is replaced by a variable *)
In[6]:= b = v*x/f-v*x/g+z
v x v x
Out[6]= --- - --- + z
f g
In[7]:= b = b /.{x_/f-x_/g -> x/h}
v x
Out[7]= --- + z
h
In[8]:=