# Runtime warning in power of np.array

Asked 5 months ago, Updated 5 months ago, 13 views

Please let me know as I was at a loss because the power of the 2D array of numpy (power by element) could not be successful.

Environment:
Python: 3.7.5
Number: 1.17.4

If you try to multiply the float32 type 2D np.array (which contains positive or negative real values, some NaNs) by 1.514, both `**` and ` np.power()` will get the following error and return np.array containing values that are not 1.514 multiplied by the element.

``````RuntimeWarning: invalid value encountered in power
``````

The foo is a float32 type, obtained in NetCDF format from a weather data distribution server.

If you take out one element and multiply it by 1.514, you will also get Runtime warning in the following description.

`````` foo** 1.514
(foo: 2D np.array)
``````

However, creating an array var in which elements are extracted and re-stored one by one in a loop using the following method, and `var**1.514` returns a normal value.

`````` var=np.zeros(len(lat),len(lon))
for i in range (len(lat)) :
for jin range (len(lon)) :
var[i][j]=foo[i][j]
(foo is the original np.array)
``````

This method will solve the problem for now, but it's creepy, so could you tell me the cause?

python numpy

2022-09-30 11:41

The numPy `power()` function does not seem to support negative or complex power.
I got caught up in the same thing and got to this question, but as I went through a lot of things, I found a similar question on the English page and made a similar guess.

This problem probably doesn't occur when squared, but if it's the 1.7th power, it's an error even if the target is not negative.

As a countermeasure for me, `abs()` takes the absolute value, which makes it a little less efficient, but I was able to deal with it.

``````z=np.power(abs(x),y)
z=abs(x)**y
``````

That's what it looks like.

2022-09-30 11:41

## If you have any answers or tips

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