The documentation for R2020B bicgstab uses right preconditioning wheras R2020A uses left preconditioning. Did the code change or is this a documentation typo?
The 'bicgstab' function uses the right preconditioner in all of the MATLAB releases.
There was a documentation and a help text issue in earlier versions. This has been resolved and the documentation page for 'bicgstab' in the newer releases of MATLAB reflects the update.
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