G. D. McBain

> In case you want to try that yourself, [amgcl/solver/cg.hpp](https://github.com/ddemidov/amgcl/blob/master/amgcl/solver/cg.hpp) should be a good starting point. (#144) Thank you for the invitation and the very informative discussion and helpful tips...

I'll add XDMF to the list of formats supporting multiple meshes. #568 #622

I confirm the issue (with meshio 4.3.2 from conda-forge). The line ```python meshio.write("modell2.msh", msh) ``` raises ``` WARNING:root:Binary Gmsh needs c_size_t (got int64). Converting. WARNING:root:Binary Gmsh needs c_size_t (got int64)....

While there might be a regression in meshio 4.3.1 reading Gmsh MSH 4.1 without physical entities #956, there might be an easy remedy in your case: just define one. I...

``` msh = meshio.read('modell.msh') meshio.write('modell2.msh',msh) WARNING:root:Binary Gmsh needs c_size_t (got int64). Converting. >>> msh2 = meshio.read('modell2.msh') Traceback (most recent call last): ``` Right, meshio 4.3.2 successfully reads `modell.msh` which contains...

I confirm that the cube, sphere, and wedge can be read, rewritten, and reread successfully by meshio 4.3.2; there's something different about the MSH 4.1 that Gmsh generates from `modell.step`.

Wow, that doesn't look good. Thank you for persisting with the investigation after your own needs have been met. I don't understand the MSH 4.1 `$Entities` myself but it is...

Although the example referred to above (with the `Xdmf Version` manually bumped from `"2.0"` to `"3.0"`) ```xml 0.0 1.0 0.0 1.0 0.0 0.0 2.0 0.0 0.0 2.0 2.0 0.0 1.0...

An intermediate issue: `meshio.XdmfReader._read_data_item` expects a `DataItem` to have an attribute `Dimensions` which it doesn't in the above because it has a `Reference` instead. #608

The switch from `lxml` to [`xml.etree.ElementTree`](https://docs.python.org/3/library/xml.etree.elementtree.html) is good but as noted in #561, it has limited support for XPath expressions, so something like ```xml /Xdmf/Domain/DataItem[@Name="Point Data"] ``` in the above...