π−p ⇒ π−π+n Amplitude Analysis and Extrapolation to the π Exchange Pole

We solve analytically for the π−p ⇒ π−π+n amplitudes in the ρ region at 17.2 GeV/c and find two acceptable solutions. We discuss the extrapolation of s and t channel amplitudes to the π pole and conclude that the former should be used for ππ phase shift analyses.