A confocal feedback system (CFS) has been modified in three ways to include space variance, time sampling, and a second feedback loop. The space-variant system performs analog solution of partial differential equations (PDE’s) with variable coefficients. The time-sampling system solves PDE’s in three dimensions. The CFS with a second feedback loop has a more flexible feedback transfer function and can solve an extended range of PDE’s. Finally, a combination of time sampling and a second feedback loop can solve four-dimensional problems. Experimental results verifying the abilities of each of these new confocal feedback systems have been obtained.
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