import os
import numpy
from numpy import *
import math
from scipy import integrate, linalg
from matplotlib import pyplot
from pylab import *

class Freestream:
    """
    Freestream conditions.
    """
    def __init__(self, u_inf=1.0, alpha=0.0):
        """
        Sets the freestream speed and angle (in degrees).
        
        Parameters
        ----------
        u_inf: float, optional
            Freestream speed;
            default: 1.0.
        alpha: float, optional
            Angle of attack in degrees;
            default 0.0.
        """
        self.u_inf = u_inf
        self.alpha = alpha*numpy.pi/180.0 # degrees to radians
