docs: public static boolean isPositiveDefinite( DMatrixRMaj A ) {
          if( !isSquare(A))
             return false;
  
          CholeskyDecompositionInner_DDRM chol = new CholeskyDecompositionInner_DDRM(true);
          if( chol.inputModified() )
              A = A.copy();
  
          return chol.decompose(A);
      }