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

Table 2

Maximum absolute pointwise error and rate of convergence for Example 2 before and after the Richardson extrapolation method applied, where .

m, n	16, 16	32, 32	64, 64	128, 128	256, 256
	After
	1.5252e − 06	5.6891e − 08	2.8561e − 09	1.5286e − 10	9.4897e − 12
	1.5252e − 06	5.6891e − 08	2.8561e − 09	1.5808e − 10	9.4897e − 12
	1.5252e − 06	5.6891e − 08	2.8561e − 09	1.5808e − 10	9.4897e − 12
	1.5252e − 06	5.6891e − 08	2.8561e − 09	1.5808e − 10	9.4897e − 12
	1.5252e − 06	5.6891e − 08	2.8561e − 09	1.5808e − 10	9.4897e − 12
	Rate of convergence
	4.7446	4.3161	4.2237	4.0581
	Before
	4.7003e − 03	1.1960e − 03	3.0108e − 04	7.5494e − 05	1.8899e − 05
	4.7003e − 03	1.1960e − 03	3.0108e − 04	7.5494e − 05	1.8899e − 05
	4.7003e − 03	1.1960e − 03	3.0108e − 04	7.5494e − 05	1.8899e − 05
	4.7003e − 03	1.1960e − 03	3.0108e − 04	7.5494e − 05	1.8899e − 05
	4.7003e − 03	1.1960e − 03	3.0108e − 04	7.5494e − 05	1.8899e − 05
	Rate of convergence
	1.9746	1.9383	1.9957	1.9980