BlockMatrix64F B = BlockMatrixOps.createRandom(4,2,-1,1,rand,3);
BlockMatrix64F B_orig = B.copy();
BlockMatrix64F X = new BlockMatrix64F(A.numRows,B.numCols,3);
solver.solve(B,X);
boolean modified = !MatrixFeatures.isEquals(B_orig,B);
assertTrue(modified == solver.modifiesB());
}