CFLib.org – Common Function Library Project

Description:
Horner's method, evaluates for given value of x for a polynomial in the form y = an*x^n + an-1*x^(n-1) + an-2*x^(n-2) + ... + a1 * x + a0

Supply as many coefficients as necessary (two required) for each decreasing power of x, using 0 for missing terms.

Return Values:
Returns a simple value.

Example:

<CFSET x = -2>
  <CFSET a4 = 2>
  <CFSET a3 = 0>
  <CFSET a2 = -3>
  <CFSET a1 = 3>
  <CFSET a0 = -4>
  <CFOUTPUT>
  Given x = -2, a4 = 2, a3 = 0, a2 = -3, a1 = 3, a0 = -4
  Polynomial(-2, 2, 0, -3, 3, -4) is #Polynomial(-2, 2, 0, -3, 3, -4)#
  </CFOUTPUT>

Parameters:

Full UDF Source:

/**
 * Evaluates the Polynomial in the form y = an * x^n + a(n-1) * x^(n-1) + ... + a1 * x + a0 for a given value of x.
 * 
 * @param x      Any real value. 
 * @param a1      Real coefficient of highest power of x. 
 * @param a0      Real coefficient of second-highest power of x. 
 * @param a...      Additional coefficients. 
 * @return Returns a simple value. 
 * @author Joel Cox (jlcox@goodyear.com) 
 * @version 1.0, July 18, 2001 
 */
function Polynomial(x, a1, a0)
{ 
    var RetVal = a1 * x + a0;  
    var arg_count = ArrayLen(Arguments);
    var opt_arg = 4;
    for( ; opt_arg LTE arg_count; opt_arg = opt_arg + 1 )
    {
        RetVal = RetVal * x + Arguments[opt_arg];
    }
    return(RetVal); 
}