Question: boundary conditions are not been utilized need help

hello friends am working on 2d heat equation and i have writen maple code for it but its not running because my scheme is having fictitious points which are removed by using boundary conditions but in this code which i have written the line in bold is not using boundary conditions due to which my fictitious points are still in programe and its not working am attaching my worksheet

trytimg.mw

please let me know where am wrong thank you

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