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I have to analyse a mass with variable acceleration. The first function defines acceleration. The second return arrays for respectively place, speed and acceleration at time t. (t goes from 0-10 with increments of 0.1)

```
import numpy as np
import matplotlib.pyplot as plt
dt = 0.1
t0 = 0.0
t1 = 10.0
x0 = 0.0
v0 = 0.0
m = 5.0
t = np.linspace(0, 10, 101)
def versnelling(t):
return (0.7 * np.sin(3 * t)) / m
def numeriek(x0, v0, a_func, t):
x = np.zeros(len(t))
v = np.zeros(len(t))
a = np.zeros(len(t))
x[0] = x0
v[0] = v0
a[0] = a_func(t[0])
for i in range(len(t) - 1):
dt = t[i + 1] - t[i]
a[i + 1] = a0 + a_func(i)
v[i + 1] = v[i] + a[i] * dt
x[i + 1] = x[i] + v[i] * dt
return x, v, a
```

But when I call it:

```
numeriek(x0, v0, versnelling(t), t)
```

I get:

```
TypeError: 'numpy.ndarray' object is not callable
```

I tried just a 0 in `a_function()`

, as well as a `t`

How do I fix it but most of all why does my code not work??

### >Solution :

The parameter `a_func`

seems to be a function, so when you call the `numeriek`

it should be passed as `versnelling`

and not `versnelling(t)`

that is in fact a function invocation resulting in a value.

```
import numpy as np
import matplotlib.pyplot as plt
dt = 0.1
t0 = 0.0
t1 = 10.0
x0 = 0.0
v0 = 0.0
m = 5.0
t = np.linspace(0, 10, 101)
def versnelling(t):
return (0.7 * np.sin(3 * t)) / m
def numeriek(x0, v0, a_func, t):
x = np.zeros(len(t))
v = np.zeros(len(t))
a = np.zeros(len(t))
x[0] = x0
v[0] = v0
a[0] = a_func(t[0])
for i in range(len(t) - 1):
dt = t[i + 1] - t[i]
a[i + 1] = a[0] + a_func(i)
v[i + 1] = v[i] + a[i] * dt
x[i + 1] = x[i] + v[i] * dt
return x, v, a
if __name__ == "__main__":
print(numeriek(x0, v0, versnelling, t))
```