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python - How to use sin(x) and cos(x) functions with eval

I need a program which can make graphs by matplotlib with functions I write in the console. But it doesn't work with trigonometric functions. The code I already wrote is:

from numpy import linspace
import matplotlib.pyplot as plt
from math import sin, cos, tan

print("input a:")
a = float(input())
print("input b:")
b = float(input())
x = linspace(a, b, 1001)
y = eval(input())

plt.plot(x, y)
plt.xlabel('x')
plt.ylabel('y')
plt.show()
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1 Answer

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by (71.8m points)

I Don't exactly understand what you want to do but that might help:

from numpy import linspace, sin, cos, tan
import matplotlib.pyplot as plt

a = float(input('Enter x0: '))
b = float(input('Enter x1: '))
x = linspace(a, b, 1001)

for trig_func in [sin, cos]:
    y = trig_func(x)
    plt.title(f'{trig_func.__name__}(x)')
    plt.plot(x, y)
    plt.xlabel('x')
    plt.ylabel('y')
    plt.show()

Please explain how you try to implement eval function..


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