how do i get values of ratios instead of the 0 matlab gives me?

how do i get values of ratios instead of the 0 matlab gives me?

Answer 1

[Star Strider]

We need to know what you are doing.

See if format long (or other format options) changes the result.

[Raymond Kazibwe]

format long does not change anything!Here's the program below close all;clc; format short A=[1 -1 -1 1 ;2 0 2 0;0 -1 -2 0;3 -3 -2 4]; b=[0;8;-8;7]; n=length(b) x=zeros(n,1) x(n)=b(n)/A(n,n)

[Star Strider]

With this code:

format short g
A=[1 -1 -1 1 ;2 0 2 0;0 -1 -2 0;3 -3 -2 4];
b=[0;8;-8;7];
n=length(b)
x=zeros(n,1)
x(n) = b(n)/A(n,n)

I get:

x =
            0
            0
            0
         1.75

as the final result.

If you want to do the division on your entire vector and matrix, this assignment:

x_mtx = bsxfun(@rdivide, b, A)

gives you this result:

x_mtx =
            0            0            0            0
            4          Inf            4          Inf
         -Inf            8            4         -Inf
       2.3333      -2.3333         -3.5         1.75