example.StokesFEM2d_example.py运行的问题

[DoooWeee-byte]

魏老师您好，我在运行example中的StokesFEM2d_example.py文件时得到如下结果： ~/fealpy/example$ python3 StokesFEM2d_example.py --degree=2 run boxmesh2d with time: 0.0004553340004349593 The 0-th computation: run serial_construct_matrix with time: 0.00810586299849092 /usr/lib/python3/dist-packages/scipy/sparse/linalg/dsolve/linsolve.py:193: MatrixRankWarning: Matrix is exactly singular warn("Matrix is exactly singular", MatrixRankWarning) The 1-th computation: run serial_construct_matrix with time: 0.03071680699940771 The 2-th computation: run serial_construct_matrix with time: 0.11721844200110354 The 3-th computation: run serial_construct_matrix with time: 0.458508179999626 [[nan nan nan nan] [nan nan nan nan]]

根据报错，可能是组装后的矩阵经过Dirichlet边界处理之后变成了奇异矩阵，请问这是什么原因？

[weihuayi]

这个例子还没有调试好