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# GOALSEEK - PowerPoint PPT Presentation

Part of Standard Excel Installation Finds the root of a scalar function. GOALSEEK. Recall that root-finding methods (e.g., bisection method, Newton’s method) rely on a change in sign of the objective function Any f(x) function used in GOALSEEK should have a well defined sign change.

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## PowerPoint Slideshow about ' GOALSEEK' - ashely-stanley

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Presentation Transcript

Finds the root of a scalar function

GOALSEEK

• Recall that root-finding methods (e.g., bisection method, Newton’s method) rely on a change in sign of the objective function

• Any f(x) function used in GOALSEEK should have a well defined sign change

Use Excel’s GOALSEEK feature to find the root of f(x) = x – cos(x) between 0 and 1.

GOALSEEK - Example

GOALSEEK - Example

Highlight cells that will be named. Under Formulas Tab select Create from Selection

GOALSEEK - Example

GOALSEEK - Example

Goal Seek found on Data Tab under “What-If Analysis”

GOALSEEK - Example

It is not installed by default

SOLVER will find a particular value, the maximum, or the minimum of a scalar function of a vector

SOLVER

Uses a gradient-based method (like Newton’s method) to find the root or the max/min

Works very well for functions that have a well-defined minimum (or maximum), like a quadratic form (a parabola)

SOLVER

Finding the Add-ins find the root or the max/minin Excel 2000

Go to Excel Options

FINDING The add-ins in Excel find the root or the max/min

Go to Add-Ins Tab on left and click Go at bottom

Finding The Add-ins in Excel find the root or the max/min

Make sure Solver Add-In is checked and click ok

Finding the SOLVER Add-in find the root or the max/min

Now go to Data tab and click on Solver on the far right

Find the minimum of find the root or the max/min

SOLVER - Example

f(x,y)=(x-5)2 + (y-5)2

Use named range to create a target cell ‘fxy’

SOLVER - Example

Type the formula into the target cell (“=(xval-5)^2 + (yval-5)^2”)

SOLVER - Example

SOLVER - Example

• Define and solve a problem by using Solver (0,0))

• On the Data Tab, click Solver (far right).

• If the Solver command is not on the Data Tab, you need to install the Solver add-in.

• In the Set Target Cell box, enter a cell reference or name for the target cell. The target cell must contain a formula.

MicroSoft Help on “SOLVER”

Solver is found on far right of Data tab

• To have the value of the target cell be as large as possible, click Max.

• To have the value of the target cell be as small as possible, click Min.

• To have the target cell be a certain value, click Value of, and then type the value in the box.

• In the By Changing Cells box, enter a name or reference for each adjustable cell, separating nonadjacent references with commas. The adjustable cells must be related directly or indirectly to the target cell. You can specify up to 200 adjustable cells.

MicroSoft Help on “SOLVER”

• To have Solver automatically propose the adjustable cells based on the target cell, click Guess.

• In the Subject to the Constraints box, enter any constraints you want to apply.

• Click Solve.

• To keep the solution values on the worksheet, click Keep Solver Solution in the Solver Results dialog box.

MicroSoft Help on “SOLVER”

Example 2: The SOLVER solution based on the target cell, click

• Tips

• You can interrupt the solution process by pressing ESC. Microsoft Excel recalculates the worksheet with the last values found for the adjustable cells.

• MicroSoft Help on “SOLVER”