making a 4 x 3 matrix with elements from a 3x7 matrix

m1 is 3x7

m2 is 4x3

need to pull 4 columns from m1 to make the 4 rows for m2

Answer 1

[David Goodmanson]

Hi Brandon,

m1 = rand(3,7)
m2 = m1(:,[1 3 4 5]).'

m1 =

    0.0357    0.6787    0.3922    0.7060    0.0462    0.6948    0.0344
    0.8491    0.7577    0.6555    0.0318    0.0971    0.3171    0.4387
    0.9340    0.7431    0.1712    0.2769    0.8235    0.9502    0.3816

m2 =

    0.0357    0.8491    0.9340
    0.3922    0.6555    0.1712
    0.7060    0.0318    0.2769
    0.0462    0.0971    0.8235

for example, where the columns have been indicated. The .' takes the transpose, and it has to be used if m1 has any complex values, because ' takes the complex conjugate transpose.

[Brandon]

Thank you, I didn't know that .' took the transpose.