How to use math function in Python-CodePudding

How to execute this code:

import numpy as np
import math

x = np.arange(1,9, 0.5)
k = math.cos(x)
print(x)

I got an error like this:

TypeError: only size-1 arrays can be converted to Python scalars

Thank you in advance.

CodePudding user response：

So this is happening because math.cos doesn't accept numpy arrays larger than size 1. That's why if you had a np array of size 1, your approach would still work.

A simpler way you can achieve the result is to use np.cos(x) directly:

import numpy as np

x = np.arange(1,9, 0.5)
k = np.cos(x)
print(x)
print(k)

If you have to use the math module, you can try iterating through the array and applying math.cos to each member of the array:

import numpy as np 
import math 

x = np.arange(1,9,0.5) 
for item in x:
    k = math.cos(item) 
    print(k) # or add to a new array/list

CodePudding user response：

You're looking for something like this?

import numpy as np 
import math 
x = np.arange(1,9, 0.5) 
for ang in x:
    k = math.cos(ang) 
    print(k)

CodePudding user response：

You are trying to pass ndarray (returned by arange) to a function, which expects just real number. Use np.cos instead.