What do you see when you try this:
help optim
I get this result.
Optimization Toolbox
Version 7.2 (R2015a) 09-Feb-2015
Nonlinear minimization of functions.
fminbnd - Scalar bounded nonlinear function minimization.
fmincon - Multidimensional constrained nonlinear minimization.
fminsearch - Multidimensional unconstrained nonlinear minimization,
by Nelder-Mead direct search method.
fminunc - Multidimensional unconstrained nonlinear minimization.
fseminf - Multidimensional constrained minimization, semi-infinite
constraints.
Nonlinear minimization of multi-objective functions.
fgoalattain - Multidimensional goal attainment optimization
fminimax - Multidimensional minimax optimization.
Linear least squares (of matrix problems).
lsqlin - Linear least squares with linear constraints.
lsqnonneg - Linear least squares with nonnegativity constraints.
Nonlinear least squares (of functions).
lsqcurvefit - Nonlinear curvefitting via least squares (with bounds).
lsqnonlin - Nonlinear least squares with upper and lower bounds.
Nonlinear zero finding (equation solving).
fzero - Scalar nonlinear zero finding.
fsolve - Nonlinear system of equations solve (function solve).
Minimization of matrix problems.
intlinprog - Mixed integer linear programming.
linprog - Linear programming.
quadprog - Quadratic programming.
Controlling defaults and options.
optimset - Create or alter optimization OPTIONS structure.
optimget - Get optimization parameters from OPTIONS structure.
Utility Routines.
color - Column partition for sparse finite differences.
fzmult - Multiplication with fundamental nullspace basis.
gangstr - Zero out 'small' entries subject to structural rank.
Graphical user interface and plot routines
optimtool - Optimization Toolbox Graphical User
Interface
optimplotconstrviolation - Plot max. constraint violation at each
iteration
optimplotfirstorderopt - Plot first-order optimality at each
iteration
optimplotresnorm - Plot value of the norm of residuals at
each iteration
optimplotstepsize - Plot step size at each iteration
See that lsqcurvefit is there. As well as...
which optimoptions
/Applications/MATLAB_R2015a.app/toolbox/shared/optimlib/optimoptions.m
So you may have had a problem with the install.
