Matrix problems with 3D plots

Given the following system of linear equations,

-3a + b -c +d + e = 0
b + c + 4e = 0
-3c + 2d + e = 0

Please use MATLAB to do the following:

Use rref command to find the general solution, express all unknowns with two variables s and t;
Plot 3-D figures to show all unknowns as functions of -1<s<1 and -1<t<1;

[Matt Fig]

Sounds like homework. What have you done so far?

[KAO YI]

>> A= [-3 1 -1 1 1; 0 1 1 0 4; 0 0 -3 2 1]

A =

    -3     1    -1     1     1
     0     1     1     0     4
     0     0    -3     2     1

>> R = rref(A)

R =

    1.0000         0         0    0.1111    1.2222
         0    1.0000         0    0.6667    4.3333
         0         0    1.0000   -0.6667   -0.3333
 this is what I got so far... but I dont quite know how to get t and s then plot into a 3D plot...

Answer 1

[Sara Hafeez]

>>  A= [-3 1 -1 1 1; 0 1 1 0 4; 0 0 -3 2 1]

A =

      -3     1    -1     1     1
       0     1     1     0     4
       0     0    -3     2     1

>> [R,jb] = rref(A)

R =

      1.0000         0         0    0.1111    1.2222
           0    1.0000         0    0.6667    4.3333
           0         0    1.0000   -0.6667   -0.3333

jb =

       1     2     3

[R,jb] = rref(A) also returns a vector jb such that:

    *

      r = length(jb) is this algorithm's idea of the rank of A.
    *

      x(jb) are the pivot variables in a linear system Ax = b.
    *

      A(:,jb) is a basis for the range of A.
    *

      R(1:r,jb) is the r-by-r identity matrix.    if true
      % code
    end