jremington:
It is unlikely that anyone on this forum has your combination of hardware, so the code can't be tested by us.You need to figure out why you are getting "inf" as a result.
Place print statements throughout the code to determine which variables do not have the values you expect.
Followed you advice and after a lot of trial and error found the issue.
function: abs()
I changed:
double voltsPerPH = (volt7 - volt4) / (7 - tempAdjusted4);
To:
double voltsPerPH = (abs(volt7 - volt4)) / (7 - tempAdjusted4);
This fixed it but the abs() function was there for a reason but even after reading up on it I don't know how to work around it