I wish to write the first equation to be able to use for a simple lsqcurvefit script.
The data which I will be using for the curve-fitting is stress (P) and stretch (Lamda) to determine the parameters u and N.
How can I write the equation for the stress such it is expressed in terms of the stretch without the subscript cu.
See the following. I wish to eliminate stretch_cu in favour of stretch without increasing the length of the current expression. Is this possible?
stress = @(x,stretch)(x(1)/3)*((3*x(2) - stretch_cu.^2)./(x(2) - stretch_cu.^2))*(stretch - stretch.^(-2));