(ctx, n)
return N
The number of good Rosser blocks needed to apply
    Turing method
    References:
    R. P. Brent, On the Zeros of the Riemann Zeta Function
    in the Critical Strip, Math. Comp. 33 (1979) 1361--1372
    T. Trudgian, Improvements to Turing Method, Math. Comp.
The number of good Rosser blocks needed to apply
    Turing method
    References:
    R. P. Brent, On the Zeros of the Riemann Zeta Function
    in the Critical Strip, Math. Comp. 33 (1979) 1361--1372
    T. Trudgian, Improvements to Turing Method, Math. Comp.
The number of good Rosser blocks needed to apply Turing method References : R . P . Brent On the Zeros of the Riemann Zeta Function in the Critical Strip Math . Comp . 33 ( 1979 ) 1361 -- 1372 T . Trudgian Improvements to Turing Method Math . Comp .
def sure_number_block(ctx, n):
    """The number of good Rosser blocks needed to apply
    Turing method
    References:
    R. P. Brent, On the Zeros of the Riemann Zeta Function
    in the Critical Strip, Math. Comp. 33 (1979) 1361--1372
    T. Trudgian, Improvements to Turing Method, Math. Comp."""
    if n < 9*10**5:
        return(2)
    g = ctx.grampoint(n-100)
    lg = ctx._fp.ln(g)
    brent = 0.0061 * lg**2 +0.08*lg
    trudgian = 0.0031 * lg**2 +0.11*lg
    N = ctx.ceil(min(brent,trudgian))
    N = int(N)
    return N
def sure_number_block ( ctx , n ) : if n < 9 * 10 ** 5 : return ( 2 ) g = ctx . grampoint ( n - 100 ) lg = ctx . _fp . ln ( g ) brent = 0.0061 * lg ** 2 + 0.08 * lg trudgian = 0.0031 * lg ** 2 + 0.11 * lg N = ctx . ceil ( min ( brent , trudgian ) ) N = int ( N ) return N