Can I rotate an array by 15 degrees?.

Can I rotate an array by 15 degrees?. Thanks

[Stephen23]

Once you define for us what that means, then yes. Please show what this matrix looks like once it has been rotated by fifteen degrees:

>> [0,1;1,0]
ans =
     0     1
     1     0

Answer 1

[Bjorn Gustavsson]

As Stephen points out you need to specify matters a bit more. Primarily what rotate by 15 degrees would mean for arrays in dimensions larger than 2.

For the 2-D case this should do it:

rotM = @(phi) [cos(phi) -sin(phi);sin(phi) cos(phi)]; rot15_a = rotM(15*pi/180)*a;

I have seen people using other notations for the rotation angle...

HTH

[Walter Roberson]

That rotM solution would be for the case where a is a 2 by something array of coordinates in which the first row was x and the bottom row was y.

[Bjorn Gustavsson]

Yes, I thought that reasonably obvious?

[Walter Roberson]

Coordinates are more often given with the x and y as columns rather than as rows.

If the reader was thinking in terms of rotating images rather than in terms of applying rotation to coordinate matrices, then they might not immediately recognize that the rotM code is not directly suitable for rotating images.

Answer 2

[Walter Roberson]

Sometimes imrotate() is what is needed.

But only sometimes.