[Tutor] matrix insertion routine for MNA

CryptoLevel9 at aol.com CryptoLevel9 at aol.com
Wed Oct 20 06:44:18 CEST 2004

I originally posted under the subject Values in matrices.  The two  responses 
that I received from that topic were excellent and helped me a  lot, but I 
have run into a problem that I did not anticipate having when I first  asked the 
question.  What I need help with now is how to assign  multiple values to the 
same locations in a  pre-constructed matrix and then sum the values at those  
points.  Unfortunately, there is no way to determine which values  will need 
to be summed before placing them into the matrix without  defeating the entire 
purpose of the program, that is why the values have to be  summed after they 
are placed in the matrix.  My rational behind writing a  program that does 
this is that I am trying to implement the MNA (Modified Nodal  Analysis) 
Algorithm (a technique for "solving" electrical circuits) in a program  making the 
assumptions that the circuit to be solved is planar, that  the user already knows 
the values for every element in the circuit  and which nodes the element is 
connected to.  I have looked through  the owners manual for numarray and saw 
that "The numarray constructor takes a data  argument, an optional type, and an 
optional shape argument. If the data argument  is a sequence, then array 
creates a new object of type numarray, and fills the array with the elements of the 
data  object. The shape of the array is determined by the size and nesting 
arrangement  of the elements of data." This gives me the impression that what  I 
am asking cannot be done by making every point in the matrix a list and  then 
summing the individual lists after the values have been placed in  them, 
which is what I thought of doing first.  I would prefer not  making any more 
variable names than I had listed in my original post in  order to keep from 
confusing myself as too what each internal variable  means.  Any help either on how 
to do what I am asking or how to circumvent  the need to sum values after they 
have placed in placed in the matrix would  be appreciated.
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