Cosine Similarity

Compute the cosine of the angle between two equal-length vectors.

Implement solve(a, b).

Returns. Return a float in $[-1,1][-1,\; 1]$. If either vector is all zeros the angle is undefined and the function returns 0.0.

Examples

Example 1

Input:

solve([1.0, 0.0], [1.0, 1.0])

Output:

0.707107

Example 2

Input:

solve([1.0, 2.0], [-1.0, -2.0])

Output:

-1.0