Question

x = [1 2 3 ; 5 6 7 ; 9 12 17]
y = [1 5 8]'

XY = [x y]

XY(2,:) = XY(2,:) - 5 * XY(1,:)
XY(3,:) = XY(3,:) - 9 * XY(1,:)
XY(1,:) = 2 * XY(1,:) + XY(2,:)
XY(2,:) = 1/2 * XY(2,:)
XY(3,:) = -3 * XY(2,:) + XY(3,:)
XY(2,:) = 2 * XY(3,:) + XY(2,:)
XY(1,:) = XY(1,:) + XY(3,:)

How can i multiply last version of this matrix's all rows by 1/2? Is there any built-in ones to perform this in MATLAB

Answer 1

Solution:

Use bsxfun to multiply all rows by 0.5 for last version of matrix. Add this line to last of code

XY(:,:) = bsxfun(@times, XY, [0.5; 0.5; 0.5])

Explanation:

Syntax: X=bsxfun(fun, A, B)

Description: The function applies the element-wise binary operation specified by the function handle fun to arrays A and B.

fun implies Binary function to apply where times represents Array multiplication