I am new to coding but I am trying to create a really simple program that will basically plot a line. 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.
```

basically this will represent a parabola where v is velocity, a is acceleration and x is time. But, I keep getting this error:

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

## Rohit Patel

From the documentation of

`raw_input`

:So what happens is that you try to multiply a string with a float, something like

`y="3" * x - 0.5 * "3" *x**2`

, which is not defined.The easiest way to circumvent this is to cast the input string to float first.

Mind that if you’re using python 3, you’d need to use

`input`

instead of`raw_input`

,