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/*
* Simple Mechanics Simulator (SiMS)
* copyright (c) 2009 Jakob Odersky
* made available under the MIT License
*/
package sims.math
import sims.geometry._
/**A 2x2 matrix.
* @param c11 component 1,1
* @param c12 component 1,2
* @param c21 component 2,1
* @param c22 component 2,2
*/
case class Matrix22(c11: Double, c12: Double, c21: Double, c22: Double) {
/**A 2x2 matrix can be created with two 2D vectors. In this case, each column is represented by a vector.
* @param c1 first column
* @param c2 second column*/
def this(c1: Vector2D, c2: Vector2D) = this(c1.x, c2.x, c1.y, c2.y)
/**Determinant of this matrix.*/
def det = c11 * c22 - c21 * c12
/**Addition.*/
def +(m: Matrix22) =
new Matrix22(c11 + m.c11, c12 + m.c12,
c21 + m.c21, c22 + m.c22)
/**Scalar multiplication.*/
def *(n: Double) =
new Matrix22(c11 * n, c12 * n,
c21 * n, c22 * n)
/**Matrix multiplication.*/
def *(m: Matrix22) =
new Matrix22(c11 * m.c11 + c12 * m.c21, c11 * m.c12 + c12 * m.c22,
c21 * m.c11 + c22 * m.c21, c21 * m.c12 + c22 * m.c22)
/**Multiplikation with a 2D vector.*/
def *(v: Vector2D) =
new Vector2D(c11 * v.x + c12 * v.y,
c21 * v.x + c22 * v.y)
/**Inverse.*/
def invert =
new Matrix22(c22 / det, -c12 / det,
-c21 / det, c11 / det)
}
object Matrix22 {
def apply(c1: Vector2D, c2: Vector2D) = new Matrix22(c1.x, c2.x, c1.y, c2.y)
}
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