```
import numpy as np
cimport numpy as np
cimport cython
from cython.parallel import *
ctypedef np.float64_t DTYPE
cdef DTYPE evaluate_objective(np.ndarray[DTYPE, ndim=2] A,np.ndarray[DTYPE, ndim=1] b,np.ndarray[DTYPE, ndim=1] x):
# TODO: Can be made even faster by using for loop can do it later though
return x.dot(A.dot(x) - b.dot(x))
cpdef DTYPE coordinate_descent(np.ndarray[DTYPE, ndim=2] A,np.ndarray[DTYPE, ndim=1] b,np.int nDim, np.int nIter=1000 ):
cdef Py_ssize_t i
cdef Py_ssize_t iter
cdef np.ndarray[DTYPE,
ndim=1] x = \
np.zeros(nDim, )
cdef DTYPE temp
# Note sure if it is the right way to do?
for iter in prange(nIter,nogil=True):
i = (iter%nDim)
temp = (b[i]-( A[:,i].dot(x)*x[i] ) + (A[i,i]*x[i]*x[i]))/A[i,i]
x[i] = np.max([0,np.min([temp,1])])
return evaluate_objective(A,b,x)
```