Let's say, now I have a 1x1 matrix, like:
M = Matrix([[2]])
How can I create a new 2x2 matrix from this, filling the all blanks with 0s? Which is:
N = Matrix([[2, 0], [0, 0]])
If it were numpy, I could use np.newaxis; however, it seems that there is no newaxis in sympy.
So, I tried:
N = M.reshape(2, 2)
I got the following error:
ValueError: Invalid reshape parameters 2 2
I found that the following expression works:
N = Matrix(2, 2, [D[0], 0, 0, 0])
However, this is a bit awkward. Is there any better way?
Please note that a scalar multiplication N = D[0] * Matrix(2, 2, [1, 0, 0, 0]) is not acceptable, since next time I may ask you to convert 2x2 to 3x3.
Use sympy.diag.
>>> import sympy as sp
>>> m = sp.Matrix([[2]])
>>> sp.diag(m, 0)
Matrix([
[2, 0],
[0, 0]])
>>> sp.diag(m, 0, 0)
Matrix([
[2, 0, 0],
[0, 0, 0],
[0, 0, 0]])
>>> sp.diag(sp.Matrix([[1, 2], [3, 4]]), 0)
Matrix([
[1, 2, 0],
[3, 4, 0],
[0, 0, 0]])