StP.val: Returns an error message if an oxygen concentration/pressure unit or
metabolic rate unit requires S or t and either is NULL, or a message if it
requires P and it is NULL.
Description
type
should be "oxy"
or "mr"
.
P.chk
- perform P out of normal range check. Only want to do this once per function.
Usage
StP.val(unit, type, S, t, P, P.chk = TRUE, msg)
Details
Also returns default value of P = 1.013253 if it is NULL.