Application: gvSIG desktop » gvSIG Document Layout

package org.gvsig.math.intervals;

public class IntervalUtils {

        /**

         * Calculates an nice round interval division. For instance, for

         * intervalLenght = 1100000 and numberOfDivisions=5,

         * the result would be 250000.

         * 

         * @param intervalLength The full interval to be divided

         * @param numberOfDivisions The exact number of divisions to perform

         * @return A nice round interval division. The calculated result

         * ensures that the whole interval length is covered by the proposed

         * division, so it always fulfills the following formula:

         *  <code>result*numberOfDivisions>=intervalLength</code>

         */

        public static double roundIntervalDivision(double intervalLength, int numberOfDivisions) {

                if (intervalLength<=0.0d || numberOfDivisions<=0) {

                        return 0.0d;

                }

                double division = intervalLength/numberOfDivisions;

                if (division==0.0d) {

                        return 0.0d;

                }

                double digitShift = Math.floor((Math.log10(division)));

                double scale = Math.pow(10, -digitShift);

                double firstSignificatDigit = Math.floor(scale*division);

                double result = firstSignificatDigit*Math.pow(10, digitShift);

                if (result*numberOfDivisions>=intervalLength) {

                        return result;

                }

                else {

                        result = (0.5+firstSignificatDigit)*Math.pow(10, digitShift);

                        if (result*numberOfDivisions>=intervalLength) {

                                return result;

                        }

                }

                result = (1+firstSignificatDigit)*Math.pow(10, digitShift);

                return result;

        }

}