Hello. I'm a new user to Sage. I am trying to create a matrix without knowing the values when it is initialized. All the examples I see have static matrices like A = matrix(QQ,2,2,[2,1,1,2]) My goal is to create a 2x2 matrix which I can then give values for later A[1][1]=5 However, I am told the vector is immutable. I am unable to find examples for what I want in the online notebooks such as http://www.sagenb.org/home/pub/2023/
I don't understand whether I need to specify a matrix space, as in sage: MS= MatrixSpace(QQ, 3, 3) sage: A=MS([[1,1,0],[1,2,0],[0,0, 3]]) sage: A [1 1 0] [1 2 0] [0 0 3] sage: A[1][1] 2 sage: A[1][1]=5 ValueError: vector is immutable; please change a copy instead (use copy()) sage: B=copy(A) sage: B[1][1]=4 ValueError: vector is immutable; please change a copy instead (use copy()) sage: version() 'Sage Version 4.6.1, Release Date: 2011-01-11' What I want to do is the equivalent to the Python commands from numpy import * zm=zeros((5,5),'complex') zm[1][1]=4 Long term, I have the program written in Python, I'm translating it to Sage in order to gain arbitrary precision. However, first I need to figure this first step out. I'm running Ubuntu 9.10, x64 Thanks in advance -- To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URL: http://www.sagemath.org
