Time.py | Python Fiddle

# --------------------------------------------------- 
#
# How much to increase cooking time at high altitudes
#
#----------------------------------------------------
# alt = altitude (feet)
# t_low = time at sea level (minutes)
# t_high = time at current altitude (minutes)
# pot_h = instant pot high pressure time at current altitude (minutes)
# pot_l = instant pot low pressure time at current altitude (minutes)

# (%*time)=0.005*atm-10    3000 to 15,000

# (%*time)=(1.666667*10**-3)*atm   0 to 3000

import math

def checkno():
     try:
          x = raw_input(ques)
          float(x)
          return(x);
     except ValueError:
          print 'This is not a number, try again'
          print
          print
          x = checkno()
          return(x);

print
print

alt = 0
t_low = 0
t_high = 0
pot_h = 0
pot_l = 0

ques = 'Enter current altitude (feet): '
x = alt
x = checkno()
alt = x
alt = float(alt)

ques = 'Enter sea level cooking time (minutes): '
x = t_low
x = checkno()
t_low = x
t_low = float(t_low)

j = 'n'

while (j <> 'y'):

#     t_high = ((0.0048*alt/100)+1)*t_low
     t_high = ((1.00016*10**-4)*alt+1.00021)*t_low

if alt < 3000:
          pot_h=((0.0016667*alt/100)+1)*t_low
     elif alt >= 3000:
          pot_h=(((0.005*alt-10)/100)+1)*t_low
     pot_l = (t_high+pot_h)/2
     
     print
     print
     print 'Cooking time at current altitude = ', "%.1f" % t_high, 'minutes'
     print
     print 'Cooking time in Instant Pot'
     print '     Low pressure setting = ', "%.1f" % pot_l, 'minutes'
     print '     High pressure setting= ', "%.1f" % pot_h, 'minutes'
     print
     print  
     print 'To end the program press y then enter'
     print 'Else to run again just press enter'
     print

j = raw_input()
     if j == 'y':
          print
          exit()
     ques = 'Enter current altitude (feet): '
     x = alt
     x = checkno()
     alt = x
     alt = float(alt)

ques = 'Enter sea level cooking time (minutes): '
     x = t_low
     x = checkno()
     t_low = x
     t_low = float(t_low)

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