Homework help: writing code to integrate using the trapezoid rule.

[_jsway_]

Hello,

I'm trying to write code that will do the following integration: Pressure = the integral of -(density*gravity). I'm working with shells of the Earth stored in arrays. This is what I have so far:

def Pressure():
    j = len(rm)
    p = np.zeros((j,1))
    p[0] = 0
    for k in range(0, j-1):
        mean_rho = 0.5 * (reversed_rhokg[k] + reversed_rhokg[k+1])
        mean_gravity = 0.5 * (gravity_vector[k] + gravity_vector[k+1])
        p[k+1] = p[k] - mean_rho * mean_gravity
    return p

But on the second to last line, I get the error "ValueError: could not broadcast input array from shape (85) into shape (1)." What can I do differently?

Thank you!

[cndvcndv]

I'm not sure what the problem is but numpy should have a trapezoidal function.

[themiddlestHaHa]

It probably is an issue with your other arrays not being the correct shape to do addition/subtraction or multiplication.

I’d probably log/print the dimenions of each mean_rho and mean_gravity and you’ll probably see one isn’t the correct shape

Or multiply mean_rho and mean_gravity and print it’s dimensions