Page 185 - Excel for Scientists and Engineers: Numerical Methods
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162 EXCEL: NUMERICAL METHODS
Figure 8-21. Calculation of a root of a function by the Newton-Raphson method
(before creating intentional circular reference).
(folder 'Chapter 08 Examples', workbook 'Roots of Equations', worksheet 'Newton-Raphson circular')
When you press ENTER after typing the formula in cell G4, the "Cannot
resolve circular references" message is displayed, and Excel displays a zero in
the cell to indicate a circular reference, as shown in Figure 8-22.
Figure 8-22. Creating an intentional circular reference.
(folder 'Chapter 08 Examples', workbook 'Roots of Equations', worksheet 'Newton-Raphson circular')
To force Excel to evaluate the circular reference, using the results of the
previous calculation cycle as start values for the next cycle, choose Options ...
from the Tools menu and choose the Calculation tab. Check the Iteration box
and enter 0 in the Maximum Change box. (The default settings are Maximum
Iterations = 100 and Maximum Change = 0.001.) When you press the OK button
the circular reference will be evaluated. The results of the calculations are shown
in Figure 8-23.
Figure 8-23. Finding a root by the Newton-Raphson method and circular reference.
(folder 'Chapter 08 Examples', workbook 'Roots of Equations', worksheet 'Newton-Raphson circular')
