Python-сообщество

def number1():
    x1=float(input('x1 '))
    y1=float(input('y1 '))
    x2=float(input('x2 '))
    y2=float(input('y2 '))
    if x1==x2:
        return 'y=inf'
    else:
        k=(y1-y2)/(x1-x2)
        b=y1-k*x1
        if b==0:
            return 'y=%.1fx' %(k) 
        else:
            return 'y=%.1fx+%.1f' % (k,b) , number1()
print (number1())

 def number1(x1,y1,x2,y2):
	if not x1 == x2:
		k = (y1-y2)/(x1-x2)
		b = y1-k*x1
		if b:
			return 'y=%.1fx+%.1f' % (k,b)
		return 'y=%.1fx' %(k)
	return 'y=inf'
  
while True:
	print(number1(
		float(input('x1 ')),
		float(input('y1 ')),
		float(input('x2 ')),
		float(input('y2 '))))