# ValueError: matmul: Input operand 1 has a mismatch in its core dimension 0,

I am new to python and programming for that matter. I am trying to solve a special type of wave equation using finite element method and carry out simulations in python. I am getting some errors which I do not understand and I need help. Below is the error and subsequently a part of the code.

ValueError                                Traceback (most recent call last)
<ipython-input-138-b33b0055e38e> in <module>
6     # Finite Element Method
7     #unew = (dt**2) * Minv @ (f*src[it]  -  K @ u) + 2*u - uold
----> 8     vnew = dt * Minv @ (f*src[it]  -  (Kv @ v) -  (Ku @ u)) + v
9     v = v, vnew
10     unew = (dt) * vnew

ValueError: matmul: Input operand 1 has a mismatch in its core dimension 0, with gufunc signature (n?,k),(k,m?)->(n?,m?) (size 2 is different from 1000)


# Time extrapolation

for it in range(nt):
# --------------------------------------
# Finite Element Method
#unew = (dt**2) * Minv @ (f*src[it]  -  K @ u) + 2*u - uold
vnew = dt * Minv @ (f*src[it]  -  (Kv @ v) -  (Ku @ u)) + v
v = v, vnew
unew = (dt) * vnew
#uold, u = u, unew
u = u, unew

# --------------------------------------
# Finite Difference Method
pnew = (dt**2) * Mfd @ ( f/dx*src[it]+ D @ p) + 2*p #- pold
p = p, pnew

# --------------------------------------
# Animation plot. Display both solutions
if not it % iplot:
for l in line1:
l.remove()
del l
for l in line2:
l.remove()
del l
line1 = plt.plot(x, v, 'k', lw=1.5, label='FEM')
line2 = plt.plot(x, p, 'r', lw=1.5, label='FDM')
plt.legend()
plt.gcf().canvas.draw()


It has to do with your coding style. Your code is too similar to mathematical notion. Issues include doing too much on single line and operator precedence in Python

vnew = dt * Minv @ (f*src[it]  -  (Kv @ v) -  (Ku @ u)) + v

term_1 = (f*src[it])  -  (Kv @ v) -  (Ku @ u)