[petsc-users] Why can't I save a diagonal matrix into a binary file via petsc4py?

[张峻溪]

My version is 3.22.0 from "petsc4py.__version__"
Here is the code:
```python
from petsc4py import PETSc
import numpy as np

vec1 = PETSc.Vec().createWithArray(np.arange(30))
mat1 = PETSc.Mat().createDiagonal(vec1)
mat1.assemble()
viewer = PETSc.Viewer().createBinary("abcde.bin", "w")
mat1.view(viewer)
viewer.destroy()
```

I find it runs without any error, but no file generated
However, if I convert mat1 to AIJ, it can be saved successfully