# numpy – Python cant multiply sequence by non-int of type float

## numpy – Python cant multiply sequence by non-int of type float

Change:

```
buf=pow(-(alpha*[D/Ds]),beta)
```

to:

```
buf=pow(-(alpha*(D/Ds)),beta)
```

This:

```
[D/Ds]
```

gives you list with one element.

But this:

```
alpha * (D/Ds)
```

computes the divisions before the multiplication with `alpha`

.

You can multiply a list by an integer:

```
>>> [1] * 4
[1, 1, 1, 1]
```

but not by a float:

```
[1] * 4.0
TypeError: cant multiply sequence by non-int of type float
```

since you cannot have partial elements in a list.

Parenthesis can be used for grouping in the mathematical calculations:

```
>>> (1 + 2) * 4
12
```