python - numpy 数组中的值表现奇怪

Question

已修复:谢谢各位，y(t) 不是 y(x) 我有代码应该模拟完美物体的轨迹，没有阻力，只有重力。 粘贴箱:https://pastebin.com/XknNBiJ9

我认为问题出在我的名为 evalPoly 的函数中，因为这是填充 y 值 numpy 数组的函数。最大值符合我的预期，但是它在数组中发生得太快，其余的都是非常大的负数

def evalPoly(coefs, xs): #Y values messed up
    """
    @function: evalPoly
    @params:
        coefs;  The coefficients, an iteratable object (List, tuple, array)
        xs;     The x values, a numpy array  
    @returns:   result; a numpy array
    @purpose:   Evaluate at xs a polynomial with coefficients in coefs.
    """
    result = 0.0
    for coef in coefs[-1::-1]:
        result = result * xs + coef
    return result

这是调用函数，以防我的逻辑不合理:

def trajectoryNoDrag(angleDeg,veloc,x0,y0): #Y values messed up
    """
    @function:  trajectoryNoDrag
    @params:    
        angleDeg (float); the angle of launch
        veloc (float); the initial velocity, x and y components
        x0 (float); the initial X pos
        y0 (float); the initial Y pos
    @returns:
        times (np.array); the time intervals
        xs (np.array); the x values
        ys (np.array); the y values
    @purpose:   Simulate the trajectory of an arrow
    """
    coefsX, coefsY = arrowPolys(angleDeg, veloc, x0, y0) #Store the coefs
    duration = quadSolve(coefsY)[0]     #flight duration
    tinc = duration * NUM_PER_SEC       #the incerments
    times = np.linspace(0,duration,tinc)    #The times
    xs = np.linspace(x0, coefsX[1] * duration, tinc)    #The x values
    ys = evalPoly(coefsY, xs)

    return times, xs, ys

变量“coefs”的构造方式是[c,b,a] 形式的二次公式的三个系数。

请帮我弄清楚为什么 y 值如此奇怪，它们工作得很好，但我不知道我做了什么来破坏这个函数。 x 值和时间是正确的，y 只是突然出错了。

Answer 1

它是时间的函数，而不是 x 的函数。 [y(t) 而不是 y(x)]。换句话说，调用 evalPoly(coefsY, times) 而不是 evalPoly(coefsY, xs)。

def trajectoryNoDrag(angleDeg,veloc,x0,y0): #Y values messed up
    """
   @function:  trajectoryNoDrag
   @params:    
       angleDeg (float); the angle of launch
       veloc (float); the initial velocity, x and y components
       x0 (float); the initial X pos
       y0 (float); the initial Y pos
   @returns:
       times (np.array); the time intervals
       xs (np.array); the x values
       ys (np.array); the y values
   @purpose:   Simulate the trajectory of an arrow
   """
    coefsX, coefsY = arrowPolys(angleDeg, veloc, x0, y0) #Store the coefs
    duration = quadSolve(coefsY)[0]     #flight duration
    tinc = duration * NUM_PER_SEC       #the incerments
    times = np.linspace(0,duration,tinc)    #The times
    xs = np.linspace(x0, coefsX[1] * duration, tinc)    #The x values
    # your polynomial evaluation below is a function of time.
    ys = evalPoly(coefsY, times)

    return times, xs, ys
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