How can I change the value of Y in the columns whare the value of X is zero in matrix ?

I have the large column of matrix XY for example

X Y

1 5

0 10

3 26

0 5

if I want to change the value of Y in the columns whare the value of X is zero like this

X Y

1 5

0 1.5

3 26

0 1.5

Which the command I need to use ?

Answer 1

[Alan Stevens]

Like this

XY = [1    5
      0    10
      3    26
      0    5];
XY(XY(:,1)==0,2) = 1.5

XY = 4×2

1.0000 5.0000 0 1.5000 3.0000 26.0000 0 1.5000

[Siwakorn Phakdee]

Thank you so much.