code: public static Complex_F64 det(ZMatrixRMaj mat  )
      {
          LUDecompositionAlt_ZDRM alg = new LUDecompositionAlt_ZDRM();
  
          if( alg.inputModified() ) {
              mat = mat.copy();
          }
  
          if( !alg.decompose(mat) )
              return new Complex_F64();
          return alg.computeDeterminant();
      }
docs: Returns the determinant of the matrix.  If the inverse of the matrix is also
  needed, then using {@link LUDecompositionAlt_ZDRM} directly (or any
  similar algorithm) can be more efficient.
  
  @param mat The matrix whose determinant is to be computed.  Not modified.
  @return The determinant.