(p-pinfinity)/(1/2rhoV^2)/Cpi=1/[1-M^2]^.5+ [M^2/1+{1-M^2}^.5]*(cpi/2)
or maybe just 1/[1-M^2]^.5
With the greatest of respect we are talking about stall recovery procedures for jet engined aircraft flying at high levels. Those of us who dare to ventue up there use a formulae that better suits our purpose, and one that is understood by those with less than level 2 English.
We know we have to sacrifice something for the screw up that just happened, irrespective of whether the fault was ours or not. If the screw up was a stall at high level....the penalty is altitude.
If we stall at high level, we are going down! Any recovery action should recognise this fact.