Math 260 Octave Information
You can find and download Octave here.
| Command |
Purpose |
Example |
| rref(A) |
Reduced row echelon form |
A = [1 2; 3 4]
rref(A) |
| * |
Multiply |
A = [1 2; 3 4]
B = [5 6 7; 8 9 10]
C = A*B |
| inv(A) |
Matrix inverse |
inv(A) OR
Ainv = inv(A) |
| lu(A) |
LU Factorization |
[L,U] = lu(A) |
| rand(n) |
Random n x n matrix |
A = rand(3) |
| det(A) |
Determinant of matrix A |
det(A) |
| eye(n) |
Identity of n x n |
I3 = eye(3) |
| \ |
Solve for x in Ax = b |
A = [1 2; 3 4]
b = [5;6]
x = A\b |
| ' |
Transpose |
Atranspose = A' |
| cond |
Condition number
(how "bad" matrix is--
1 is best, larger is worse) |
k = cond(A) |
| eig |
Eigenvalues and
eigenvectors |
A = [1 2; 3 4]
[V,L] = eig(A) |
| qr |
QR factorization |
A = [1 2; 3 4]
[Q,R] = qr(A) |
| surf, etc. |
Plot 3D function |
x = linspace(-2,2,20);
y = x';
z = x .* exp(-x.^2 - y.^2);
surf(x,y,z)
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