Java Algorithms How to - Compute the area of a triangle using Heron's Formula

• Back to Number  ↑

Question

We would like to know how to compute the area of a triangle using Heron's Formula.

Answer

//from  w  ww.ja va  2 s  . c om


  

/** Compute the area of a triangle using Heron's Formula.
 * Code and values from Prof W. Kahan and Joseph D. Darcy.
 * See http://www.cs.berkeley.edu/~wkahan/JAVAhurt.pdf.
 * Derived from listing in Rick Grehan's Java Pro article (October 1999).
 * Simplified and reformatted by Ian Darwin.
 */
public class Heron {
  public static void main(String[] args) {
    // Sides for triangle in float
    float af, bf, cf;
    float sf, areaf;

    // Ditto in double
    double ad, bd, cd;
    double sd, aread;

    // Area of triangle in float
    af = 12345679.0f;
    bf = 12345678.0f;
    cf = 1.01233995f;

    sf = (af+bf+cf)/2.0f;
    areaf = (float)Math.sqrt(sf * (sf - af) * (sf - bf) * (sf - cf));
    System.out.println("Single precision: " + areaf);

    // Area of triangle in double
    ad = 12345679.0;
    bd = 12345678.0;
    cd = 1.01233995;

    sd = (ad+bd+cd)/2.0d;
    aread =        Math.sqrt(sd * (sd - ad) * (sd - bd) * (sd - cd));
    System.out.println("Double precision: " + aread);
  }
}

The code above generates the following result.

• Back to Number  ↑