Matvec Users’ Guide

3.4. COMPUTATION 27
reshape
A.reshape(m,n) returns a new matrix of m rows and n columns, whose elements are taken from the matrix A
row-by-row. If the matrix A doesn’t have enough elements, then the operation cycles back to the beginning
of A to get enough values for the new matrix. For example,
> A = [1,0,0,0];
> B = A.reshape(3,3)
Col 1 Col 2 Col 3
Row 1 1 0 0
Row 2 0 1 0
Row 3 0 0 1
> C = A.reshape(3,4)
Col 1 Col 2 Col 3 Col 4
Row 1 1 0 0 0
Row 2 1 0 0 0
Row 3 1 0 0 0
resize
A.resize(m, n), Matrix A is resized to be m-by-n. The contents in A could be garbage.
rot90
A.rot90(k) rotate the matrix A counterclockwise k*90 degrees.
This member function is a user-defined function, it’s loaded automatically into memory whenever you
launch Matvec.
For example,
> A = [1,2,3;4,5,6;7,8,9]
Col 1 Col 2 Col 3
Row 1 1 2 3
Row 2 4 5 6
Row 3 7 8 9
> A.rot90()
Col 1 Col 2 Col 3
Row 1 3 6 9
Row 2 2 5 8
Row 3 1 4 7
> A.rot90(1)
Col 1 Col 2 Col 3
Row 1 3 6 9
Row 2 2 5 8
Row 3 1 4 7
sample
A.sample() replaces its elements with random numbers from UniformDist(0.0,1.0). A.sample(m,n) first
resizes matrix A to m by n, then replaces its elements with random numbers from UniformDist(0.0,1.0).