Why do I get "ufunc 'multiply' did not contain a loop with signature matching types dtype('S32') dtype('S32') dtype('S32')" with values from raw_input

Question

I am trying to create a really simple program that will plot a plot a parabola where v is velocity, a is acceleration and x is time. The user will input values for v and a, then v and a and x will determine y.

I attempted to do this with this:

x = np.linspace(0., 9., 10)
a = raw_input('Acceleration =')
v = raw_input('Velocity = ')
y = v * x - 0.5 * a * x**2.

But, I keep getting this error:

TypeError: ufunc 'multiply' did not contain a loop with signature matching types dtype('S32') dtype('S32') dtype('S32')

What does this mean?

Answer 1

I faced this problem recently, change the dtype of x to something specific by doing:

x = np.asarray(x, dtype='float64')