def delta(pab,xt,yt):
    a = pab[0];
    b = pab[1];
    yc = [0 for i in range(len(xt))]
    for i in range(len(xt) - 1):
        yc[i] = a * xt[i] + b
    e = list(abs(yt[i] - yc[i]) for i in range(len(yt)))
    cr = sum(list(e[i] / yt[i] for i in range(len(yt)))) / len(xt)
#     print cr
    return cr

def mre(xt, yt):
    ll = len(xt)
    am, aM, bm, bM = adm(xt, yt)
    lb = [am, bm]
    rb = [aM, bM]
    vv =[] ; feas = []
    p = 20
    for i in range(p):
        feas += [[0, 0]]
        for j in range(len(lb)):
            feas[i][j] = (rb[j] - lb[j]) * np.random.uniform() + lb[j]
    count = 0; iters = 200; funp = 0
    for j in range(1, p):
        vv.append(delta(feas[j], xt, yt))
    funi = np.min(vv); ini = np.argmin(vv)
    soli = feas[ini]
    si = 0.5
    flag = 1; count = 0; si = 1
    while count < iters:
        count += 1
        for i in range(len(feas)):
            for j in range(len(feas[i])):
                feas[i][j] = feas[i][j] + si * np.random.randn()
        vec = [0]*p
        for i in range(p):
            feas[i] = max(lb, feas[i])
            feas[i] = min(rb, feas[i])
            vec[i] = delta(feas[i],xt,yt)
        fun = np.min(vec); init = np.argmin(vec)
        sol = feas[init]
        wf, wi = np.max(vec), np.argmax(vec)
#         print wi, len(feas), len(vec)
        wun = feas[wi]
        if wf > funi:
            feas[wi] = soli
            vec[wi] = funi
        if fun < funi:
            soli = sol
            funi = fun
        if count % 1000 == 0:
            print soli, residvar
    a = soli[0]
    b = soli[1]
    return a, b, funi

q = mre(datab, data)
print q