Page 424 - Excel for Scientists and Engineers: Numerical Methods

APPENDIX 3 CUSTOM FUNCTIONS HELP FILE 40 1

Bairstow
Returns an array of the roots, both real and imaginary, of a regular polynomial of
maximum order six. A regular polynomial is one that contains only integer powers of x.

Syntax
Ba i rStow( equation, variable)
equation reference to a cell containing the formula F(x) of a regular polynomial
variable cell reference corresponding to x, the independent variable

Remarks
The argument equation can be either a reference to a cell that contains a formula,
or a name.
The argument variable must be a reference to a cell.
The workbook can be set to either RlC1- or Al-style.
The Bairstow function is an array function. To return the roots of a polynomial of
order N, you must select a range of cells 2 columns by N rows, enter the function
and then press CONTROL+SHIFT+ENTER (Windows) or COMMAND+RETURN or
CONTROL+SHI~+RETURN (Macintosh).
The table of results contains the real part of the root in the first column, the
imaginary part in the second column.

Limitations
The function cannot handle implicit references; that is, a name or range reference
cannot be used for a range of values.

See Also
NewtRaph, GoalSeek