Add more benchmarks

[anthonyclays]

Current benchmarks are not entirely representative of the performance, as simple vectorized computations are easily compiled to near-perfect machine code.

Some benchmark suggestions:

• Linear algebra routines (SVD, matrix inverse, eigenvalues...)
• Number theory functions (primality tests, integer factorization...)
• Optimization (test using rosenbrock function, count the number of objective function calls)

[anthonyclays]

• For testing performance of complex numbers, you can compute the mandelbrot fractal into a 2D array.