Question

I have a basic question:
There are two lists named a1 and b1.
If I print out one item of each list, it would be a float number, but when I use a1[i]*b1[i] in a loop, it gives an error:

TypeError: can't multiply sequence by non-int of type 'float'

Why is that?

Answer 1

Either a1 or b1 is not list of floats but a list of lists of floats.

a1=[1.234, 1.234];
a2=[1.234, 1.234];
>>> a1[0]*a2[0]
1.522756

a3=[[1.234], [1.234]];

>>> a1[0]*a3[0]
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
TypeError: can't multiply sequence by non-int of type 'float'