How to rotate this 2d matrix with some angle ?

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

Answer 1

[DGM]

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]

but how to store the result as a new rotated matrix?

[DGM]

You can access the XData, etc from the graphics object. I'll update the answer...

[shubham kumar gupta]

Thank you

Answer 2

[Jan]

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.

See: https://www.mathworks.com/matlabcentral/fileexchange/66446-rotation-matrix

[shubham kumar gupta]

can you help how to apply value for u,v?

alpha i chose as 5 degree

z is matrix of 25x25

zRotated = RotMatrix(5,1,z);

not working

[Jan]

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.