Function File: vfzero (fun, x0)

Function File: vfzero (fun, x0, options)

Function File: [x, fval, info, output] = vfzero (…)

A variant of fzero. Finds a zero of a vector-valued multivariate function where each output element only depends on the input element with the same index (so the Jacobian is diagonal).

fun should be a handle or name of a function returning a column vector. x0 should be a two-column matrix, each row specifying two points which bracket a zero of the respective output element of fun.

If x0 is a single-column matrix then several nearby and distant values are probed in an attempt to obtain a valid bracketing. If this is not successful, the function fails. options is a structure specifying additional options. Currently, vfzero recognizes these options: "FunValCheck", "OutputFcn", "TolX", "MaxIter", "MaxFunEvals". For a description of these options, see optimset.

On exit, the function returns x, the approximate zero and fval, the function value thereof. info is a column vector of exit flags that can have these values:

• 1 The algorithm converged to a solution.
• 0 Maximum number of iterations or function evaluations has been reached.
• -1 The algorithm has been terminated from user output function.
• -5 The algorithm may have converged to a singular point.

output is a structure containing runtime information about the fzero algorithm. Fields in the structure are:

• iterations Number of iterations through loop.
• nfev Number of function evaluations.
• bracketx A two-column matrix with the final bracketing of the zero along the x-axis.
• brackety A two-column matrix with the final bracketing of the zero along the y-axis.

Package: optim