public void testSum() {
DenseMatrix A = new DenseMatrix(new double[][] {{1, 9}, {7, 3}});
assertTrue(new DenseMatrix(new double[][] {{8, 12}}).equals(A.sumOverRows()));
assertTrue(new DenseMatrix(new double[][] {{10}, {10}}).equals(A.sumOverCols()));
SparseMatrixLil B = A.toSparseLil();
assertTrue(new DenseMatrix(new double[][] {{8, 12}}).toSparseLil().equals(B.sumOverRows()));
assertTrue(new DenseMatrix(new double[][] {{10}, {10}}).toSparseLil().equals(B.sumOverCols()));
assertTrue(B.sumOverRows().equals(A.sumOverRows()));
assertTrue(B.sumOverCols().equals(A.sumOverCols()));
assertEquals(B.sum().sum().s(), A.sum().sum().s());
SparseMatrixLil C = spzeros(4, 5);
C.append(1, 2, 5);
C.append(3, 1, 3);
C.append(3, 2, 7);
C.append(1, 4, 11);
System.out.println(C.sumOverRows());
assertTrue(new DenseMatrix(new double[][] {{0, 3, 12, 0, 11}}).equals(C.sumOverRows()));
System.out.println(C.sumOverCols());
assertTrue(new DenseMatrix(new double[][] {{0}, {16}, {0}, {10}}).equals(C.sumOverCols()));
assertEquals(26.0, C.sumOverCols().sumOverRows().s());
assertEquals(26.0, C.sumOverRows().sumOverCols().s());
}
public static final DenseMatrix varOverCols(SparseMatrixLil mat) {
return mat.pow(2).sumOverCols().sub(mat.sumOverCols().pow(2).div(mat.cols)).div(mat.cols - 1);
}
public static final DenseMatrix meanOverCols(SparseMatrixLil mat) {
return mat.sumOverCols().div(mat.cols);
}