Overflow in ipykernel

def obj_gradA(w,x,y):
    grad = []
    yh = yhat(x,w)
    for j in range(len(w)):
        tmp = 0
        for i in range(len(x)):
            tmp = tmp+yh[i]*(y[i]-yh[i])*(1-yh[i])*x[i,j]
        grad.append(-2*tmp)
    return np.array(grad)

def obj_gradB(w,x,y):
    grad = []
    yh = yhat(x,w)
    tmp = yh*(y-yh)*(1-yh)
    for j in range(len(w)):
        grad.append(-2*np.sum(tmp*x[:,j]))
    return np.array(grad)

def obj_gradC(w,x,y):
    yh = yhat(x,w)
    return -2*np.dot(yh*(y-yh)*(1-yh,x))

from scipy.optimize import minimize
w_start = np.random.rand(*w_exact.shape)
w_found = minimize(obj, w_start, method = 'Nelder-Mead',args=(x_rand,y))
print(w_found)
print('exact val', w_exact)
 final_simplex: (array([[ 1806.07992755,  -358.33266465],
       [ 1806.07999633,  -358.33267886],
       [ 1806.07999898,  -358.33267909]]), array([-6.67715058, -6.67715058, -6.67715058]))
           fun: -6.6771505843807075
       message: 'Optimization terminated successfully.'
          nfev: 195
           nit: 78
        status: 0
       success: True
             x: array([ 1806.07992755,  -358.33266465])
exact val [5 3]
C:\ProgramData\Anaconda3\lib\site-packages\ipykernel\__main__.py:2: RuntimeWarning: overflow encountered in exp
  from ipykernel import kernelapp as app