A Nonstandard Fitted Operator Method for Singularly Perturbed Parabolic Reaction-Diffusion Problems with a Large Time Delay

Table 1

Maximum absolute pointwise error and rate of convergence for Example 1 before and after the Richardson extrapolation method applied, where .

m, n	10, 10	20, 20	40, 40	80, 80	160, 160
	After
	5.7318e − 06	3.3273e − 07	2.0558e − 08	1.2776e − 09	7.9666e − 11
	5.7318e − 06	3.3273e − 07	2.0558e − 08	1.2776e − 09	7.9666e − 11
	5.7318e − 06	3.3273e − 07	2.0558e − 08	1.2776e − 09	7.9666e − 11
	5.7318e − 06	3.3273e − 07	2.0558e − 08	1.2776e − 09	7.9666e − 11
	5.7318e − 06	3.3273e − 07	2.0558e − 08	1.2776e − 09	7.9666e − 11
	Rate of convergence
	4.1066	4.0166	4.0081	4.0034
	Before
	8.3948e − 03	2.3134e − 03	6.0360e − 04	1.5393e − 04	3.8852e − 05
	8.3948e − 03	2.3134e − 03	6.0360e − 04	1.5393e − 04	3.8852e − 05
	8.3948e − 03	2.3134e − 03	6.0360e − 04	1.5393e − 04	3.8852e − 05
	8.3948e − 03	2.3134e − 03	6.0360e − 04	1.5393e − 04	3.8852e − 05
	8.3948e − 03	2.3134e − 03	6.0360e − 04	1.5393e − 04	3.8852e − 05
	Rate of convergence
	1.8595	1.9383	1.9713	1.9862