def compute_shell_and_tube_material_factor(A, a, b):
    """
    Return the material factor for shell and tubes given the area [A; ft^3]
    and material-dependent coefficients `a` and `b`. 
    
    Notes
    -----
    Material factors are computed using Eq. 16.44 in [1]_:
    
    :math:`F_M = a + \\left(\\frac{A}{100.0}\\right)^b`
    
    """
    return a + (A / 100.0) ** b
