Add 8 3 math is very wrong, programming works

README.md

@@ -19,5 +19,7 @@ Dateien wie Bilder die zur Lösung einer Aufgabe gehören sind in <br><ins>Medie
 
 
 - Keine
+## Notizen
+- part8 aufg3 matrix.multiplyMatrix is mathematically completely wrong
 ## Fragen
 - Was können die in Interfaces definierten Variablen?

src/part8/aufg3/matrix.java

@@ -0,0 +1,90 @@
+package part8.aufg3;
+
+public class matrix {
+    private int rows;
+    private int cols;
+    int[][] field;
+
+    matrix(int rows, int cols){
+        this.rows = rows;
+        this.cols = cols;
+
+        field = new int[rows][cols];
+    }
+
+    public int getCols() {
+        return cols;
+    }
+
+    public int getRows() {
+        return rows;
+    }
+
+    void print(){
+        for (int i=0; i<this.rows; i++){
+            for (int j=0; j<this.cols; j++){
+                System.out.print(field[i][j]);
+                if (j != this.cols-1) {
+                    System.out.print(" ; ");
+                }
+            }
+            System.out.println();
+        }
+        System.out.println("===========");
+    }
+
+    void setValue(int row, int col, int value){field[row][col] = value;}
+
+    int getValue(int row, int col){return field[row][col];}
+
+    void scalarMultiply(int factor){
+        for (int i=0; i<this.rows; i++) {
+            for (int j = 0; j < this.cols; j++) {
+                field[i][j] *= factor;
+            }
+        }
+    }
+
+    void addMatrix(matrix matrix2){
+        for (int i=0; i<this.rows; i++) {
+            for (int j = 0; j < this.cols; j++) {
+                field[i][j] += matrix2.field[i][j];
+            }
+        }
+    }
+
+    boolean multiplyMatrix(matrix matrix2){
+        boolean compatible = false;
+
+        if(this.getRows() == matrix2.getCols()){
+            compatible = true;
+            matrix result = new matrix(this.getRows(), matrix2.getCols());
+
+
+            result.print();
+        }
+
+        return compatible;
+    }
+
+    public static void main(String[] args){
+        matrix nr1 = new matrix(2,3);
+        matrix nr2 = new matrix(2,3);
+
+        nr1.setValue(1,1,1);
+        nr2.setValue(0,0,4);
+
+        nr2.addMatrix(nr1);
+        nr2.print();
+
+        nr2.scalarMultiply(8);
+        nr2.print();
+
+        nr2.scalarMultiply(7);
+        nr2.print();
+
+        matrix nr3 = new matrix(7,4);
+        matrix nr4 = new matrix(6,7);
+        System.out.println(nr3.multiplyMatrix(nr4));
+    }
+}