regarding leasqr

[preeti gaikwad]

Hello all, 

              I am the new user in fitting please help me to solve my query. I am using leasqr to estimate parameters from the experimental data. 

my fuction is

s=A.*exp(-x./tabs).*(D./D0).^2.*exp(-(pi*pi).*(D.*x)./L.^2);

where D is

D=(D0.*tloc.^(a))./(tloc.^(m).+x.^(m)).^(a./m);

I would like to calculate

A = p(6);% constant value

D0=p(2);

tloc=p(3);

a=p(4);

m=p(5);

 Using the leasqr

[f, p] = leasqr(t, y, pin,'conv_fnc', tolerance, max_iterations, weights, dp, dFdp, options);

unfortunately i am getting value whatever is my pin

like my pin is

pin = [0.5 25 0.000000005 1 7 1000 0]

and for all value of x I have straight line like but my experimental data is exponential decreasing function.

and the defined fuction is s also exponential decay function. My quest is why leasqr is not giving the new calculated value from the fun s???? THANKS FOR YOUR HELP in advance.

regards P