arduiono calibs

WPA1 = (4.093+(3.2113*(r/1000)))/(1-(0.009733*(r/1000))-(.01205*25))

# WPA2 has 3 equations conditional on risistance and according to
# https://www.kimberly.uidaho.edu/water/swm/Calibration_Watermark2.htm#_ftnref2

if (r >= 0 and r < 1000):
    WPA2 = -20*((r/1000)*(1+.018*(25-T))-.55)

elif(r >=1000 and r < 8000):
    WPA2 = (-3.213*(r/1000) - 4.093) / (1-.009733*(r/1000)-.01205*T)

elif(r >= 8000):
    WPA2 = -2.246 - (5.239*(r/1000)*(1+.018*(T-24))) - .06756*pow((r/1000),2)*pow((1+.018*(T-24)),2)




#(5)
WPA3 = -6.44 - ((4.196*(r/1000)-2.098) / (1-.013*T))

#(7) for WaterMark Model 200
WPA4 = -(4.691 + 3.559*(r/1000)) / (1-.008456*T)

#(8) for WaterMark Model 200SS
WPA5 = -(4.093 + 3.213*(r/1000)) / (1-.009733*(r/1000) -.01205*T)

#(9) for WaterMark Model 200SSX 
WPA6 = -(4.734 + 2.859*(r/1000)) / (1-.01856*(r/1000) - .01316*T)