Create topoplot_bug.md

Author: arnodelorme

others/topoplot_bug.md

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+In EEGLAB 2024.0,l we modified the topoplot function for Octave compatibility, where the meshgrid function was used to precompute point coordinates (this is the [code change](https://github.com/sccn/eeglab/commit/fb2b77e1db70c025b7898f18af895e59aba7bbc1) to fix the issue). This is because Octave griddata function is not as powerful as the MATLAB one and requires this extra step.
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+However, the coordinates were inverted, resulting in the bug below. This is a subtle mirroring issue in which the image is flipped along the diagonal.
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+![scalp_topo](https://github.com/sccn/sccn.github.io/assets/1872705/0e9003b5-203e-431c-ada5-6bf1c31a2051)
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+Unfortunately, this issue affects all topoplot performed with EEGLAB 2024.0.