python - RecursionError: maximum recursion depth exceeded -

i'm working on building python script solve riemann's paradox. idea take inputted number, , add or subtract 1/2,1/3,1/4,1/5... to/from 1 until have inputted number. i'm running recursion error result of calling comparison , adding/subtracting classes every time comparison made.

my code follows:

import math #declare values of variables before referenced goal = float(input("what number trying achieve?")) current_number = float(1) negatives = (2) positives = (3) #----------------------------------------------------- def add(goal,current_number,positives,negatives): #define add operation when current number less goal     current_number = current_number+(1/positives) #add current fraction current number     positives = positives+2 #set next additional fraction     comparison(goal,current_number,positives,negatives) #go comparision of current number goal  def subtract(goal,current_number,positives,negatives): #define subtract operation when current number greater goal     current_number = current_number-(1/negatives) #subtract current fraction current number     negatives = negatives+2 #set next subtractional fraction     comparison(goal,current_number,positives,negatives) #go comparision of current number goal  def comparison(goal,current_number,positives,negatives): #define comparison between current number goal     if current_number < goal:         add(goal,current_number,positives,negatives) #if current number less goal, go add next fraction     if current_number > goal:         subtract(goal,current_number,positives,negatives) #if current number greater goal, subtract next fraction     if current_number == goal:         print("the equation number 1+1/3...")         print("+1/",positives)         print("...-1/2...")         print("-1/",negatives)         #if current number equal goal, print results  comparison(goal,current_number,positives,negatives) #do comparison between current number , goal 

i'm wondering can solve problem.

you don't need function add , subtract because adding negative same subtracting.

also have fixed code, calling function calls function called causing recursion error.

hope helps :)

import math goal = float(input("what number trying achieve?"))  current_number = 0 fraction = 2 #----------------------------------------------------- def change(goal, current_number, fraction, sign = 1): #define add operation when current number less goal     global positives     current_number = current_number + (1/fraction) * sign # add or take away current fraction current number     return current_number  def comparison(goal, current_number, fraction): #define comparison between current number goal     print("the equation number is:")     print("1/2")     while round(current_number, 3) != round(goal, 3): # don't have round if don't want         fraction = fraction + 1         if current_number < goal:             print("+1/"+str(fraction)) # positive             current_number = change(goal, current_number, fraction) #if current number less goal, go add next fraction         elif current_number > goal:             print("-1/"+str(fraction)) # positive             current_number = change(goal, current_number, fraction, -1)     print("...")  comparison(goal,current_number, fraction) #do comparison between current number , goal