Asymptotes and exponential decay functions

Does anyone know how to write a script for an exp decay and get the asymptote value as well?

[Walter Roberson]

Which asymptote? Substitute +inf or -inf for "t" to get those asymptote. Asymptote near a singularity is more difficult.

[Lynn Knoblauch]

Thank you for your response. I am VERY novice at this. I may be confused/ wondering if the estimates for the y axis intercept are calculated as the the y-intercept minus asymptote. But I think I need an entirely different code for this. Right now I am working with:

time = [0.009 0.01 0.012 0.0150 0.0167 0.02 0.023 ];

SWA = [11 10 9 8 7.5 7.1 6.9 ];

    %set up exp equation

    expdecay = @(EXD,xx)(EXD(1)*exp(-EXD(2)*xx));

    %initial value cross

    EXD = [SWA(1) 2];

    %nlinfit to calc EXD(1) and EXD(2) in fitting

    expfit = nlinfit(time,SWA,expdecay, EXD) 

hrfit = min(time):0.001:max(time);

swafit = expdecay(expfit,hrfit);

figure(1)

plot(time,SWA,'ok','markerfacecolor','m','markersize',5)

hold on
plot(hrfit,swafit,':x')

hold off

xlabel('time across night')

ylabel('SWA')