import math
import matplotlib.pyplot as plt

#把原函数换成题干的形式########################
def fx(x):
    return math.exp(x)-math.sin(x)

# 绘制函数图像 并标记可能的零点
def DrawGraph(a, b, stepper):
    x = [a + (b-a)*i*stepper for i in range(int(1/stepper+1))]
    y = [fx(i) for i in x]
    plt.xlim(a-abs(b-a)*0.1, b+abs(b-a)*0.1)
    plt.plot(x, y)
    plt.axhline(0, color='black', lw=0.5, ls='-')
    plt.axvline(a, color='red', lw=0.5, ls='--')
    plt.axvline(b, color='red', lw=0.5, ls='--')
    plt.text(a, y[0], f'({a:.5f},{y[0]:.5f})', fontsize=8, ha='left')
    plt.text(b, y[-1], f'({b:.5f},{y[-1]:.5f})', fontsize=8, ha='right')
    for i in range(len(x)-1):
        if y[i] * y[i+1] < 0:
            print(f"可能存在零点: ({x[i]:.5f},{y[i]:.5f})和({x[i+1]:.5f},{y[i+1]:.5f})之间")
            plt.plot((x[i]+x[i+1])/2, (y[i]+y[i+1])/2, 'ro', markersize=3)
    plt.title("Graph of f(x)")
    plt.xlabel("x")
    plt.ylabel("f(x)")
    plt.show()
    return x, y

#把范围改成题干的形式#######################
if __name__ == "__main__":
    a = -2*math.pi
    b = math.pi
    step = 0.00001
    print(f"边界点: {a}, {b}")
    print(f"步长: {step}")
    x, y = DrawGraph(a, b, step)