Added methods to get and set elements, rows, columns.

Also clarified the element naming scheme, which is mCOLROW.

src/main/java/pythagoras/d/IMatrix3.java

@@ -13,33 +13,42 @@ import pythagoras.util.SingularMatrixException;
  */
 interface IMatrix3
 {
-    /** Returns the (0,0)th component of the matrix. */
+    /** Returns column 0, row 0 of the matrix. */
     double m00 ();
 
-    /** Returns the (1,0)th component of the matrix. */
+    /** Returns column 1, row 0 of the matrix. */
     double m10 ();
 
-    /** Returns the (2,0)th component of the matrix. */
+    /** Returns column 2, row 0 of the matrix. */
     double m20 ();
 
-    /** Returns the (0,1)th component of the matrix. */
+    /** Returns column 0, row 1 of the matrix. */
     double m01 ();
 
-    /** Returns the (1,1)th component of the matrix. */
+    /** Returns column 1, row 1 of the matrix. */
     double m11 ();
 
-    /** Returns the (2,1)th component of the matrix. */
+    /** Returns column 2, row 1 of the matrix. */
     double m21 ();
 
-    /** Returns the (0,2)th component of the matrix. */
+    /** Returns column 0, row 2 of the matrix. */
     double m02 ();
 
-    /** Returns the (1,2)th component of the matrix. */
+    /** Returns column 1, row 2 of the matrix. */
     double m12 ();
 
-    /** Returns the (2,2)th component of the matrix. */
+    /** Returns column 2, row 2 of the matrix. */
     double m22 ();
 
+    /** Returns the matrix element at the specified row and column. */
+    double element (int row, int col);
+
+    /** Copies the requested row (0, 1, 2) into {@code result}. */
+    void getRow (int row, Vector3 result);
+
+    /** Copies the requested column (0, 1, 2) into {@code result}. */
+    void getColumn (int col, Vector3 result);
+
     /**
      * Transposes this matrix.
      *

src/main/java/pythagoras/d/Matrix3.java

@@ -18,7 +18,7 @@ public class Matrix3 implements IMatrix3, Serializable
     /** the identity matrix. */
     public static final Matrix3 IDENTITY = new Matrix3();
 
-    /** The values of the matrix. */
+    /** The values of the matrix. The names take the form {@mCOLROW}. */
     public double m00, m10, m20;
     public double m01, m11, m21;
     public double m02, m12, m22;
@@ -55,6 +55,74 @@ public class Matrix3 implements IMatrix3, Serializable
         setToIdentity();
     }
 
+    /**
+     * Sets the matrix element at the specified row and column.
+     */
+    public void setElement (int row, int col, double value) {
+        switch (col) {
+        case 0:
+            switch (row) {
+            case 0: m00 = value; return;
+            case 1: m01 = value; return;
+            case 2: m02 = value; return;
+            }
+            break;
+        case 1:
+            switch (row) {
+            case 0: m10 = value; return;
+            case 1: m11 = value; return;
+            case 2: m12 = value; return;
+            }
+            break;
+        case 2:
+            switch (row) {
+            case 0: m20 = value; return;
+            case 1: m21 = value; return;
+            case 2: m22 = value; return;
+            }
+            break;
+        }
+        throw new ArrayIndexOutOfBoundsException();
+    }
+
+    /**
+     * Sets the specified row (0, 1, 2) to the supplied values.
+     */
+    public void setRow (int row, double x, double y, double z) {
+        switch (row) {
+        case 0: m00 = x; m10 = y; m20 = z; break;
+        case 1: m01 = x; m11 = y; m21 = z; break;
+        case 2: m02 = x; m12 = y; m22 = z; break;
+        default: throw new ArrayIndexOutOfBoundsException();
+        }
+    }
+
+    /**
+     * Sets the specified row (0, 1, 2) to the supplied vector.
+     */
+    public void setRow (int row, Vector3 v) {
+        setRow(row, v.x(), v.y(), v.z());
+    }
+
+    /**
+     * Sets the specified column (0, 1, 2) to the supplied values.
+     */
+    public void setColumn (int col, double x, double y, double z) {
+        switch (col) {
+        case 0: m00 = x; m01 = y; m02 = z; break;
+        case 1: m10 = x; m11 = y; m12 = z; break;
+        case 2: m20 = x; m21 = y; m22 = z; break;
+        default: throw new ArrayIndexOutOfBoundsException();
+        }
+    }
+
+    /**
+     * Sets the specified column (0, 1, 2) to the supplied vector.
+     */
+    public void setColumn (int col, Vector3 v) {
+        setColumn(col, v.x(), v.y(), v.z());
+    }
+
     /**
      * Sets this matrix to the identity matrix.
      *
@@ -398,6 +466,54 @@ public class Matrix3 implements IMatrix3, Serializable
         return m22;
     }
 
+    @Override // from IMatrix3
+    public double element (int row, int col) {
+        switch (col) {
+        case 0:
+            switch (row) {
+            case 0: return m00;
+            case 1: return m01;
+            case 2: return m02;
+            }
+            break;
+        case 1:
+            switch (row) {
+            case 0: return m10;
+            case 1: return m11;
+            case 2: return m12;
+            }
+            break;
+        case 2:
+            switch (row) {
+            case 0: return m20;
+            case 1: return m21;
+            case 2: return m22;
+            }
+            break;
+        }
+        throw new ArrayIndexOutOfBoundsException();
+    }
+
+    @Override // from IMatrix3
+    public void getRow (int row, Vector3 result) {
+        switch (row) {
+        case 0: result.x = m00; result.y = m10; result.z = m20; break;
+        case 1: result.x = m01; result.y = m11; result.z = m21; break;
+        case 2: result.x = m02; result.y = m12; result.z = m22; break;
+        default: throw new ArrayIndexOutOfBoundsException();
+        }
+    }
+
+    @Override // from IMatrix3
+    public void getColumn (int col, Vector3 result) {
+        switch (col) {
+        case 0: result.x = m00; result.y = m01; result.z = m02; break;
+        case 1: result.x = m10; result.y = m11; result.z = m12; break;
+        case 2: result.x = m20; result.y = m21; result.z = m22; break;
+        default: throw new ArrayIndexOutOfBoundsException();
+        }
+    }
+
     @Override // from IMatrix3
     public Matrix3 transpose () {
         return transpose(new Matrix3());

src/main/java/pythagoras/d/Matrix4.java

@@ -21,7 +21,7 @@ public final class Matrix4 implements IMatrix4, Serializable
     /** An empty matrix array. */
     public static final Matrix4[] EMPTY_ARRAY = new Matrix4[0];
 
-    /** The values of the matrix. */
+    /** The values of the matrix. The names take the form {@mCOLROW}. */
     public double m00, m10, m20, m30;
     public double m01, m11, m21, m31;
     public double m02, m12, m22, m32;

src/main/java/pythagoras/f/IMatrix3.java

@@ -13,33 +13,42 @@ import pythagoras.util.SingularMatrixException;
  */
 interface IMatrix3
 {
-    /** Returns the (0,0)th component of the matrix. */
+    /** Returns column 0, row 0 of the matrix. */
     float m00 ();
 
-    /** Returns the (1,0)th component of the matrix. */
+    /** Returns column 1, row 0 of the matrix. */
     float m10 ();
 
-    /** Returns the (2,0)th component of the matrix. */
+    /** Returns column 2, row 0 of the matrix. */
     float m20 ();
 
-    /** Returns the (0,1)th component of the matrix. */
+    /** Returns column 0, row 1 of the matrix. */
     float m01 ();
 
-    /** Returns the (1,1)th component of the matrix. */
+    /** Returns column 1, row 1 of the matrix. */
     float m11 ();
 
-    /** Returns the (2,1)th component of the matrix. */
+    /** Returns column 2, row 1 of the matrix. */
     float m21 ();
 
-    /** Returns the (0,2)th component of the matrix. */
+    /** Returns column 0, row 2 of the matrix. */
     float m02 ();
 
-    /** Returns the (1,2)th component of the matrix. */
+    /** Returns column 1, row 2 of the matrix. */
     float m12 ();
 
-    /** Returns the (2,2)th component of the matrix. */
+    /** Returns column 2, row 2 of the matrix. */
     float m22 ();
 
+    /** Returns the matrix element at the specified row and column. */
+    float element (int row, int col);
+
+    /** Copies the requested row (0, 1, 2) into {@code result}. */
+    void getRow (int row, Vector3 result);
+
+    /** Copies the requested column (0, 1, 2) into {@code result}. */
+    void getColumn (int col, Vector3 result);
+
     /**
      * Transposes this matrix.
      *

src/main/java/pythagoras/f/Matrix3.java

@@ -18,7 +18,7 @@ public class Matrix3 implements IMatrix3, Serializable
     /** the identity matrix. */
     public static final Matrix3 IDENTITY = new Matrix3();
 
-    /** The values of the matrix. */
+    /** The values of the matrix. The names take the form {@mCOLROW}. */
     public float m00, m10, m20;
     public float m01, m11, m21;
     public float m02, m12, m22;
@@ -55,6 +55,74 @@ public class Matrix3 implements IMatrix3, Serializable
         setToIdentity();
     }
 
+    /**
+     * Sets the matrix element at the specified row and column.
+     */
+    public void setElement (int row, int col, float value) {
+        switch (col) {
+        case 0:
+            switch (row) {
+            case 0: m00 = value; return;
+            case 1: m01 = value; return;
+            case 2: m02 = value; return;
+            }
+            break;
+        case 1:
+            switch (row) {
+            case 0: m10 = value; return;
+            case 1: m11 = value; return;
+            case 2: m12 = value; return;
+            }
+            break;
+        case 2:
+            switch (row) {
+            case 0: m20 = value; return;
+            case 1: m21 = value; return;
+            case 2: m22 = value; return;
+            }
+            break;
+        }
+        throw new ArrayIndexOutOfBoundsException();
+    }
+
+    /**
+     * Sets the specified row (0, 1, 2) to the supplied values.
+     */
+    public void setRow (int row, float x, float y, float z) {
+        switch (row) {
+        case 0: m00 = x; m10 = y; m20 = z; break;
+        case 1: m01 = x; m11 = y; m21 = z; break;
+        case 2: m02 = x; m12 = y; m22 = z; break;
+        default: throw new ArrayIndexOutOfBoundsException();
+        }
+    }
+
+    /**
+     * Sets the specified row (0, 1, 2) to the supplied vector.
+     */
+    public void setRow (int row, Vector3 v) {
+        setRow(row, v.x(), v.y(), v.z());
+    }
+
+    /**
+     * Sets the specified column (0, 1, 2) to the supplied values.
+     */
+    public void setColumn (int col, float x, float y, float z) {
+        switch (col) {
+        case 0: m00 = x; m01 = y; m02 = z; break;
+        case 1: m10 = x; m11 = y; m12 = z; break;
+        case 2: m20 = x; m21 = y; m22 = z; break;
+        default: throw new ArrayIndexOutOfBoundsException();
+        }
+    }
+
+    /**
+     * Sets the specified column (0, 1, 2) to the supplied vector.
+     */
+    public void setColumn (int col, Vector3 v) {
+        setColumn(col, v.x(), v.y(), v.z());
+    }
+
     /**
      * Sets this matrix to the identity matrix.
      *
@@ -398,6 +466,54 @@ public class Matrix3 implements IMatrix3, Serializable
         return m22;
     }
 
+    @Override // from IMatrix3
+    public float element (int row, int col) {
+        switch (col) {
+        case 0:
+            switch (row) {
+            case 0: return m00;
+            case 1: return m01;
+            case 2: return m02;
+            }
+            break;
+        case 1:
+            switch (row) {
+            case 0: return m10;
+            case 1: return m11;
+            case 2: return m12;
+            }
+            break;
+        case 2:
+            switch (row) {
+            case 0: return m20;
+            case 1: return m21;
+            case 2: return m22;
+            }
+            break;
+        }
+        throw new ArrayIndexOutOfBoundsException();
+    }
+
+    @Override // from IMatrix3
+    public void getRow (int row, Vector3 result) {
+        switch (row) {
+        case 0: result.x = m00; result.y = m10; result.z = m20; break;
+        case 1: result.x = m01; result.y = m11; result.z = m21; break;
+        case 2: result.x = m02; result.y = m12; result.z = m22; break;
+        default: throw new ArrayIndexOutOfBoundsException();
+        }
+    }
+
+    @Override // from IMatrix3
+    public void getColumn (int col, Vector3 result) {
+        switch (col) {
+        case 0: result.x = m00; result.y = m01; result.z = m02; break;
+        case 1: result.x = m10; result.y = m11; result.z = m12; break;
+        case 2: result.x = m20; result.y = m21; result.z = m22; break;
+        default: throw new ArrayIndexOutOfBoundsException();
+        }
+    }
+
     @Override // from IMatrix3
     public Matrix3 transpose () {
         return transpose(new Matrix3());

src/main/java/pythagoras/f/Matrix4.java

@@ -21,7 +21,7 @@ public final class Matrix4 implements IMatrix4, Serializable
     /** An empty matrix array. */
     public static final Matrix4[] EMPTY_ARRAY = new Matrix4[0];
 
-    /** The values of the matrix. */
+    /** The values of the matrix. The names take the form {@mCOLROW}. */
     public float m00, m10, m20, m30;
     public float m01, m11, m21, m31;
     public float m02, m12, m22, m32;