Peak detection

Hi,

I have a signal and know i need to get the corresponding time and peaks from it and i have no idea how can i do this. can someone help me? Thanks, Flavia

i=sqrt(-1);
f=0.1; %Hz
fs=1000;% Sampling in Hz
ta=1/fs;
t=0:ta:100;
T=10;
U=100*sqrt(2)*sin(2*pi*f*t); %V
c=1e-6; %F
C=-2*pi*f*c*i; 
R=15e6*(1+exp(-(t/T+log(5/3))))-14e6; %Ohm
Y=(1./R)+C;
Z=1./Y;
I=c*(gradient(U)/ta)+(U./R);
plot(t,I/2e-7,'r');