def vtas2cas(tas, h):
    """ tas2cas conversion both m/s """
    p, rho, T = vatmos(h)
    qdyn = p*((1.+rho*tas*tas/(7.*p))**3.5-1.)
    cas = np.sqrt(7.*p0/rho0*((qdyn/p0+1.)**(2./7.)-1.))

    # cope with negative speed
    cas = np.where(tas<0, -1*cas, cas)
    return cas
def vtas2cas ( tas , h ) : p , rho , T = vatmos ( h ) qdyn = p * ( ( 1. + rho * tas * tas / ( 7. * p ) ) ** 3.5 - 1. ) cas = np . sqrt ( 7. * p0 / rho0 * ( ( qdyn / p0 + 1. ) ** ( 2. / 7. ) - 1. ) ) cas = np . where ( tas < 0 , - 1 * cas , cas ) return cas
tas2cas conversion both m/s