%Ultrasonic
global f R0 P0 Pv Pa ki PI rou sigma mu omiga 
PI=3.1415926;                      
rou=1000;  
ki=1.0;
sigma=0.072;                        
mu=1.*10^(-3);                            
Pv=2340; 
P0=1.013*10^5;
Pa=1.013*10^5;
R0=3.15.*10^(-6);
f=0.75*10^6;
omiga=2*PI*f
time=1./f;
ttime=6.*time
options=odeset('RelTol',1e-4,'AbsTol',[1e-4 1e-4]);
[t,y]=ode45('diffrpnnp2',[0 ttime],[R0;0.],options);
plot((t*f),y(:,1)/R0);
xlabel('Time/T');ylabel('Soluntion R(t)/R0');
legend('R=R(t)/R0');