# How to rotate this 2d matrix with some angle ?

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shubham kumar gupta on 19 Nov 2022
Commented: Jan on 20 Nov 2022
I tried to make a mesh using this
z=peaks(100);
// Now z is a 100x100 matrix
Now I want to roatate this in some angle like 5 degress
I tried this for
z = peaks(2);
theta = 5;
R = [cosd(theta) -sind(theta); sind(theta) cosd(theta)];
z1=R*z;
but for z greater than 2x2 not working
this i want

DGM on 19 Nov 2022
Edited: DGM on 19 Nov 2022
You'll need more than zdata to rotate the plot. You'll need to define the x and y positions of the points.
If you just want to rotate the plot, you can just use rotate(). It's up to you to pick the view position you want.
[x y z] = peaks(20);
theta = 15;
hs = mesh(x,y,z);
axis equal
% pick some view vector
% [0 1 0] rotation vector is || to y-axis
% [-3 0 0] origin of rotation vector
rotate(hs,[0 1 0],-theta,[-3 0 0])
view([0 -1 0]) % set the view
axis equal
xlabel('x')
% get the rotated data
xr = hs.XData;
yr = hs.YData;
zr = hs.ZData;
shubham kumar gupta on 19 Nov 2022
Thank you

Jan on 19 Nov 2022
Edited: Jan on 19 Nov 2022
To define a rotation matrix, you need
• one angle in 2D (rotation around the Z axis)
• one angle and an axis of rotation in 3D
• one angle and 2 vectors, which build the plane to rotate in in 4D and higher dimensions. Rotating "around an axis" is not uniquely defined in >= 4D.
##### 2 CommentsShowHide 1 older comment
Jan on 20 Nov 2022
Please read the documentation of the provided command: help RotMatrix. The input (5,1,z) are not meaningful. The angle is provided in radians, not degrees. With 3 inputs, you ask for a rotation matrix in a higher dimensional case. Then the 2nd and 3rd argument are two vectors which span the plane to rotate in.
I cannot suggest values vor u and v as long as you do not define the plane to rotate in. But I think, you do not want to rotate in a 25-dimensional space, but still in 2D.

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