Here we see how to do constrained optimization with an Excel spreadsheet function. The spreadsheet function MinimizeNonnegative() imposes a nonnegativity constraint on the variable. This is useful when you’re solving for something that can’t be negative, like energy or an interest rate.
The Excel Solver is a powerful tool for solving complicated problems. But what if you want something smaller and more compact like… an Excel spreadsheet function? Minimize() combines the power of a nonlinear optimizer with the convenience of a spreadsheet function. Unlike the Excel Solver or Goal Seek, it responds to changes in the values of its arguments and recalculates automatically like any other formula in the spreadsheet. As an added bonus, Minimize() can optimize some things that the Excel Solver cannot.
Math for Mere Mortals 