How can I input negative number without a string error in Python (The input must be in tuples) [closed]

Question

def eqQuadratic(Variables):
      valuesoflinear=Variables[1]
      a = float(valuesoflinear[0])
      b = float(valuesoflinear[2])
      c = float(valuesoflinear[4])
      x = float(valuesoflinear[6])

      y = a*x**2 + b*x + c
      return y

input2 = input("input a, x, b, c to calculate the quadratic equation ")
Variables = ("The input for quadratic equation are ", input2)
y = eqQuadratic(Variables)
print("the answer for quadratic equation is ", y)

If I input all positive numbers it works, but if I input negative numbers, it won't works.

I get this error

Traceback (most recent call last): File "C:/Users/maxime/Desktop/SESAME/PycharmProjects/Neocortex0.0/dj.py", line 14, in y = eqQuadratic(Variables) File "C:/Users/maxime/Desktop/SESAME/PycharmProjects/Neocortex0.0/dj.py", line 3, in eqQuadratic a = float(valuesoflinear[0]) ValueError: could not convert string to float: '-'

How can I have the 4 different values from the input()command and convert them into float number.

Answer 1

The error is that you don't ask for 4 number. so the valuesoflinear[0] is just a sign -. You need to ask 4 number that can be negartive like -1

here a solution :

def eqQuadratic(Variables):
    a = float(Variables[0])
    b = float(Variables[1])
    c = float(Variables[2])
    x = float(Variables[3])

    y = a * x ** 2 + b * x + c
    return y


inputa = input("input a to calculate the quadratic equation ")
inputx = input("input x to calculate the quadratic equation ")
inputb = input("input b to calculate the quadratic equation ")
inputc = input("input c to calculate the quadratic equation ")
# Variables = ("The input for quadratic equation are ", input2)
y = eqQuadratic([inputa,inputx,inputb,inputc])
print("the answer for quadratic equation is ", y)

You can ask for several input in a row but you have to be careful if less or more than 4 parameters are enter

def eqQuadratic(Variables):
    a = float(Variables[0])
    b = float(Variables[1])
    c = float(Variables[2])
    x = float(Variables[3])

    y = a * x ** 2 + b * x + c
    return y


input2 = input("input a, x, b, c to calculate the quadratic equation ").split()
# Variables = ("The input for quadratic equation are ", input2)
if not len(input2) == 4:
    print('you need to enter 4 param')
else:
    y = eqQuadratic(input2)
    print("the answer for quadratic equation is ", y)