Discontinuous temperature correction in O3

[theGOTOguy]

In the field we noticed a dramatic shift in measured O3 PPM and realized it was due to the temperature correction being discontinuous at 0C. For instance, consider your code:

    elif self.gastype == DFRobot_GasType.O3:
      if (self.temp > -20) and (self.temp <= 0):
        Con = Con / (0.015 * self.temp + 1.1) - 0.05
      elif (self.temp > 0) and (self.temp <= 20):
        Con = Con/1.1 - (0.01 * self.temp)
      elif (self.temp > 20) and (self.temp <= 40):
        Con = Con/1.1 - (-0.005 * self.temp + 0.3)
      else:
         Con = 0.0

We expect Con / (0.015 * self.temp + 1.1) - 0.05 to equal Con/1.1 - (0.01 * self.temp) at self.temp == 0.

However, let's try letting Con = 1 and see what we get:

ben@anteater:~$ ipython3
Python 3.12.3 (main, Feb  4 2025, 14:48:35) [GCC 13.3.0]
Type 'copyright', 'credits' or 'license' for more information
IPython 8.20.0 -- An enhanced Interactive Python. Type '?' for help.

In [1]: 1 / (0.015 * 0  + 1.1) - 0.05
Out[1]: 0.859090909090909

In [2]: 1 / 1.1 - (0.01 * 0)
Out[2]: 0.9090909090909091

There is clearly an issue in the concentration calculations if they are not continuous at the temperature boundaries.