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POstuck trying to write a method to multiply matrices
 

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  1. POstuck trying to write a method to multiply matrices
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    <pre><code>public class Homework2 { public static void main(String[] args){ int num1 = (int) (Math.random()*(10-3+1)+3); int num2 = (int) (Math.random()*(10-3+1)+3); double[][] doubMatrix1 = new double[num1][num2]; double[][] doubMatrix2 = new double[num1][num2]; double[][] doubMatrix3 = new double[num1][num2]; doubMatrix1 = getdoubMatrix(num1,num2); doubMatrix2 = getdoubMatrix(num1,num2); doubMatrix3 = addMatrices(doubMatrix1, doubMatrix2, num1, num2); printDoubMatrix("First matrix", doubMatrix1); printDoubMatrix("Second matrix", doubMatrix2); printDoubMatrix("Result of adding", doubMatrix3); doubMatrix2 =transposeMatrix(num1,num2, doubMatrix2); printDoubMatrix("Second matrix transposed", doubMatrix2); doubMatrix3 = multipyMatrices(doubMatrix1, doubMatrix2, num1, num2); printDoubMatrix("Result of multiplying", doubMatrix3); } public static double[][] getdoubMatrix(int num1,int num2){ double[][] tempArray = new double[num1][num2]; for(int i = 0;i &lt; tempArray.length;i++) for(int j = 0;j &lt; tempArray[i].length;j++) { tempArray[i][j] = Math.random() * (100); } return tempArray; } public static double[][] addMatrices(double[][] doubMatrix1, double[][] doubMatrix2,int num1,int num2) { double[][] tempArray = null; if(doubMatrix1.length == doubMatrix2.length) if(doubMatrix1[0].length == doubMatrix2[0].length) { tempArray = new double[num1][num2]; for(int i = 0; i&lt; doubMatrix1.length;i++) for(int j = 0; j&lt; doubMatrix1[i].length;j++ ) { tempArray[i][j] = doubMatrix1[i][j] + doubMatrix2[i][j]; } } else { return tempArray = new double[0][0]; } return tempArray; } public static void printDoubMatrix(String text,double[][] doubMatrix1){ System.out.println(text); for(int i = 0; i&lt; doubMatrix1.length;i++) { for(int j = 0; j&lt; doubMatrix1[i].length;j++ ) { System.out.printf("%9.1f", doubMatrix1[i][j]); } System.out.println(); } } public static double[][] transposeMatrix(int num1, int num2, double[][] doubMatrix2){ double[][] tempArray = new double[num2][num1]; for(int i = 0;i &lt; num1;i++) for(int j = 0;j &lt; num2;j++) { tempArray[j][i] = doubMatrix2[i][j]; } return tempArray; } public static double[][] multipyMatrices(double[][] doubMat1, double[][] doubMat2, int num1, int num2) { double[][] tempArray = null; if(doubMat1[0].length == doubMat2.length) { tempArray = new double[num1][num2]; for(int i = 0; i&lt; doubMat1.length;i++) for(int j = 0; j &lt; doubMat1[i].length;j++ ) for(int k = 0; k &lt;doubMat1[i].length;k++ ) { tempArray[i][j] = tempArray[i][j] + doubMat1[i][k]*doubMat2[k][j]; } } else { return tempArray = new double[0][0]; } return tempArray; } </code></pre> <p>}</p> <p>ok I have narrowed my code down to a error at the for loop where it said j in the last method,but i really don't know how to fix it. Can anyone suggest a way to make this code work. The statement to multiply matrices is not wrong also the row for loop is not wrong </p> <p>my multiply method output the samething as my transposed method which is not correct, well I think that J ranges over the second index of doubMat2</p> <p>here is my output</p> <p>First matrix</p> <pre><code> 55.8 58.8 18.6 5.0 34.6 97.6 8.8 8.4 71.1 63.3 15.7 63.9 41.8 89.2 1.0 54.5 36.5 68.5 55.8 21.3 40.1 10.0 67.2 37.8 45.9 95.5 76.0 98.2 11.2 20.8 8.3 78.3 44.8 81.2 32.8 58.0 7.9 57.2 22.2 92.6 90.0 93.2 73.7 5.2 20.1 13.3 73.0 30.3 63.2 9.1 72.1 75.3 53.3 45.6 86.6 85.4 Second matrix 12.2 76.0 7.3 87.8 8.9 23.6 67.1 65.4 22.0 91.3 96.0 59.6 76.4 82.0 51.2 29.5 39.2 70.9 6.8 1.5 78.0 52.6 47.3 29.5 1.4 95.8 15.4 43.9 27.1 79.7 26.7 14.6 47.0 52.6 80.4 65.7 88.8 46.5 60.9 82.6 4.9 9.9 47.9 21.7 55.4 67.1 26.3 90.1 90.0 96.0 15.7 92.9 74.9 22.8 17.3 53.9 Result of adding 68.0 134.8 25.9 92.8 43.4 121.1 75.8 73.8 93.1 154.6 111.7 123.5 118.2 171.2 52.2 84.0 75.7 139.4 62.6 22.8 118.0 62.6 114.5 67.3 47.3 191.2 91.4 142.1 38.3 100.6 35.0 92.9 91.8 133.7 113.2 123.7 96.7 103.6 83.2 175.2 94.9 103.1 121.6 26.9 75.5 80.4 99.3 120.4 153.2 105.1 87.8 168.2 128.2 68.4 103.9 139.2 Second matrix transposed 12.2 65.4 51.2 52.6 27.1 65.7 47.9 96.0 76.0 22.0 29.5 47.3 79.7 88.8 21.7 15.7 7.3 91.3 39.2 29.5 26.7 46.5 55.4 92.9 87.8 96.0 70.9 1.4 14.6 60.9 67.1 74.9 8.9 59.6 6.8 95.8 47.0 82.6 26.3 22.8 23.6 76.4 1.5 15.4 52.6 4.9 90.1 17.3 67.1 82.0 78.0 43.9 80.4 9.9 90.0 53.9 Result of multiplying 12.2 65.4 51.2 52.6 27.1 65.7 47.9 96.0 76.0 22.0 29.5 47.3 79.7 88.8 21.7 15.7 7.3 91.3 39.2 29.5 26.7 46.5 55.4 92.9 87.8 96.0 70.9 1.4 14.6 60.9 67.1 74.9 8.9 59.6 6.8 95.8 47.0 82.6 26.3 22.8 23.6 76.4 1.5 15.4 52.6 4.9 90.1 17.3 67.1 82.0 78.0 43.9 80.4 9.9 90.0 53.9 </code></pre>
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    1. PTQuestion
    1. USKhoa Vo
    1. USKhoa Vo
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    1. COAre you going to tell what problem are you having?
      singulars
      1. POstuck trying to write a method to multiply matrices
      1. USRohit Jain
    2. COoh sorry about that
      singulars
      1. POstuck trying to write a method to multiply matrices
      1. USKhoa Vo
    3. COmy code run without error,It just doesn't print out the right output
      singulars
      1. POstuck trying to write a method to multiply matrices
      1. USKhoa Vo
 

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