function f = tank37(t,z)
% this file defines the dimesionless model of the enclosed tank vessel
% in section 3.7.
%

%
% initial values:
%
P1=1.0; P3=0.785;

Vg = 2-z;
Tg = (1/Vg)^0.343;
Pg = 0.735*Tg/Vg;

P2 = Pg + 0.2167*z;
F1 = 4.541*sqrt(P1-P2);
F2 = 4.541*sqrt(P2-P3);
f = F1 - F2;
