The minimum of Eq. 3, 𝚫𝚫𝐩𝐩, is obtained using the MATLAB syntax 𝚫𝚫𝐩𝐩 = -𝛁𝛁𝛁𝛁𝛁𝛁\𝛁𝛁𝛁𝛁 𝐓𝐓 where "\" corresponds to the MATLAB function mldivide, which solves the linear system of equations in Eq. 6. Note that 𝛁𝛁𝛁𝛁𝛁𝛁 may not be invertible on occasion. As is standard practice with nonlinear fitting routines, 𝚫𝚫𝐩𝐩 undergoes a quality check at the end of each iteration to ensure the move is productive. In particular, the program uses a backtracking line search subject to the Armijo condition. And finally, the program compares the new position 𝐩𝐩 𝐢𝐢+𝟏𝟏 = 𝐩𝐩 𝐢𝐢 + 𝚫𝚫𝐩𝐩 to the parameter boundaries provided by the user and corrects 𝚫𝚫𝐩𝐩 if necessary.