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A new application of Taylor expansion for approximate solution of systems of Fredholm integral equations Cover

A new application of Taylor expansion for approximate solution of systems of Fredholm integral equations

By: Mohsen Didgar and  Farzan Ekhlasi  
Open Access
|Jan 2026

Figures & Tables

Fig. 1

The exact solutions (solid) versus the approximate solutions (dashed) for m = 1.
The exact solutions (solid) versus the approximate solutions (dashed) for m = 1.

Fig. 2

The exact solutions (solid) versus the approximate solutions (dashed) for m = 2.
The exact solutions (solid) versus the approximate solutions (dashed) for m = 2.

Fig. 3

The exact solutions (solid) versus the approximate solutions (dashed) for m = 3.
The exact solutions (solid) versus the approximate solutions (dashed) for m = 3.

Fig. 4

Variations of the errors between several approximations of ψ1(x) and the corresponding exact value.
Variations of the errors between several approximations of ψ1(x) and the corresponding exact value.

Fig. 5

Variations of the errors between several approximations of ψ2(x) and the corresponding exact value.
Variations of the errors between several approximations of ψ2(x) and the corresponding exact value.

Absolute errors of Application 5 by rationalized Haar functions method in [28] for (ψ1(x), ψ2(x))_

xM=16M=32
0.1(5.98 × 10−3, 2.40 × 10−4)(9.44 × 10−3, 1.07 × 10−3)
0.2(1.89 × 10−2, 4.12 × 10−3)(3.18 × 10−3, 7.00 × 10−4)
0.3(1.85 × 10−2, 5.12 × 10−3)(3.08 × 10−3, 8.60 × 10−4)
0.4(6.41 × 10−3, 2.62 × 10−3)(9.34 × 10−3, 3.56 × 10−3)
0.5(3.11 × 10−2, 1.44 × 10−2)(1.56 × 10−2, 7.36 × 10−3)
0.6(6.18 × 10−3, 3.53 × 10−3)(9.39 × 10−3, 5.32 × 10−3)
0.7(1.87 × 10−2, 1.20 × 10−2)(3.13 × 10−3, 1.98 × 10−3)
0.8(1.87 × 10−2, 1.35 × 10−2)(3.13 × 10−3, 2.31 × 10−3)
0.9(6.17 × 10−3, 4.45 × 10−3)(9.40 × 10−3, 7.42 × 10−3)
1.0(3.13 × 10−2, 2.65 × 10−2)(1.56 × 10−2, 1.32 × 10−2)

Absolute errors of Application 1 for ψ1(x)_

xMethod in [31] (m=10)Suggested methodSuggested methodSuggested method
|ψExactψTaylor|m=1m=2m=3
0.12.548 × 10−42.89365 × 10−18.76658 × 10−20
0.21.055 × 10−31.69063 × 10−15.32303 × 10−20
0.31.558 × 10−39.81397 × 10−22.99342 × 10−20
0.41.513 × 10−35.38480 × 10−21.52024 × 10−20
0.51.467 × 10−32.82321 × 10−26.67616 × 10−30
0.62.634 × 10−31.73289 × 10−22.29812 × 10−30
0.76.293 × 10−31.93255 × 10−23.73043 × 10−40
0.81.248 × 10−23.43349 × 10−24.01271 × 10−40
0.91.655 × 10−26.45784 × 10−29.36226 × 10−40
1.04.620 × 10−31.14521 × 10−11.79048 × 10−30

Absolute errors of Application 2 for ψ2(x)_

xMethod in [26]Suggested methodSuggested method
|ψExactψADM|m=1m=2
0.13.45 × 10−36.25429 × 10−20
0.26.90 × 10−31.00914 × 10−10
0.31.03 × 10−21.18371 × 10−10
0.41.38 × 10−21.18171 × 10−10
0.51.72 × 10−21.03571 × 10−10
0.62.07 × 10−27.78286 × 10−20
0.72.41 × 10−24.42000 × 10−20
0.82.76 × 10−25.94286 × 10−30
0.93.10 × 10−23.36857 × 10−20
1.03.45 × 10−27.14286 × 10−20

Absolute errors of Application 4 for ψ1(x)_

xm=1m=2m=3m=4
0.11.42576 × 10−11.87892 × 10−11.18936 × 10−21.07546 × 10−2
0.21.02909 × 10−11.50166 × 10−18.40862 × 10−34.51723 × 10−3
0.37.28585 × 10−21.16840 × 10−15.75061 × 10−33.13013 × 10−3
0.45.11274 × 10−28.77018 × 10−23.77465 × 10−32.06896 × 10−3
0.53.66628 × 10−26.25978 × 10−22.34919 × 10−31.28032 × 10−3
0.62.87143 × 10−24.14305 × 10−21.35764 × 10−37.21594 × 10−4
0.72.69156 × 10−22.41633 × 10−26.98557 × 10−43.52211 × 10−4
0.83.13962 × 10−21.08267 × 10−22.86319 × 10−41.33281 × 10−4
0.94.29419 × 10−21.52918 × 10−35.19763 × 10−52.75368 × 10−5
1.06.32297 × 10−23.52550 × 10−35.55572 × 10−56.06983 × 10−7

The maximum of the absolute errors in [59] by collocation method_

xcos x
1.91 × 10−21.02 × 10−2

Absolute errors of Application 3 by B-spline wavelet method in [40] for (ψ1(x), ψ2(x))_

xM=2M=4
0.1(2.07979E – 6, 1.04205E – 4)(8.12417E – 9, 6.51057E – 6)
0.2(1.94288E – 6, 1.14576E – 3)(7.58937E – 9, 7.16143E – 5)
0.3(1.80597E – 6, 1.14572E – 3)(7.05456E – 9, 7.16142E – 5)
0.4(1.66906E – 6, 1.04308E – 4)(6.51976E – 9, 6.51097E – 6)
0.5(1.53215E – 6, 2.60434E – 3)(5.98496E – 9, 1.62761 E – 4)
0.6(1.39524E – 6, 1.04367E – 4)(5.45016E – 9, 6.51120E – 6)
0.7(1.25833E – 6, 1.14561 E – 3)(4.91536E – 9, 7.16137E – 5)
0.8(1.12142E – 6, 1.14558E – 3)(4.38055E – 9, 7.16136E – 5)
0.9(9.84513E – 7, 1.04438E – 4)(3.84575E – 9, 6.51148E – 6)
1.0(8.47603E – 7, 2.60446E – 3)(3.31095E – 9, 1.62762E – 4)

Absolute errors of Application 5 for (ψ1(x), ψ2(x))_

xm=1m=2
0.1(6.39030 × 10−3, 4.89613 × 10−2)(5.03104 × 10−4, 3.35710 × 10−3)
0.2(9.88092 × 10−4, 4.28668 × 10−2)(1.21393 × 10−4, 3.29583 × 10−3)
0.3(2.53419 × 10−3, 3.56531 × 10−2)(1.91079 × 10−4, 3.02207 × 10−3)
0.4(4.35938 × 10−3, 2.79192 × 10−2)(3.97546 × 10−4, 2.57961 × 10−3)
0.5(4.69526 × 10−3, 2.02420 × 10−2)(4.84346 × 10−4, 2.02815 × 10−3)
0.6(3.76983 × 10−3, 1.31603 × 10−2)(4.59428 × 10−4, 1.43648 × 10−3)
0.7(1.82537 × 10−3, 7.15873 × 10−3)(3.50314 × 10−4, 8.75759 × 10−4)
0.8(8.88641 × 10−4, 2.65294 × 10−3)(2.01529 × 10−4, 4.12923 × 10−4)
0.9(4.12378 × 10−3, 2.38319 × 10−5)(7.16129 × 10−5, 1.04535 × 10−4)
1.0(7.64147 × 10−3, 6.32640 × 10−4)(2.97710 × 10−5, 8.93103 × 10−6)

Absolute errors of Application 1 by B-spline wavelet method in [40] for (ψ1 (x), ψ2(x))_

xM=2M=4
0.1(1.05947E – 4, 3.16487E – 4)(6.51740E – 6, 5.47084E – 6)
0.2(1.14356E – 3, 1.75687E – 3)(7.16057E – 5, 1.16058E – 4)
0.3(1.14313E – 3, 2.26496E – 3)(7.16040E – 5, 1.34611 E – 4)
0.4(1.07237E – 4, 3.70402E – 5)(6.52242E – 6, 1.72473E – 5)
0.5(2.60757E – 3, 6.50994E – 3)(1.62774E – 4, 4.06899E – 4)
0.6(1.07887E – 4, 4.83014E – 4)(6.52497E – 6, 1.53021 E – 5)
0.7(1.14179E – 3, 3.46452E – 3)(7.15988E – 5, 2.23463E – 4)
0.8(1.14144E – 3, 3.97184E – 3)(7.15974E – 5, 2.42013E – 4)
0.9(1.08955E – 4, 2.05924E – 4)(6.52915E – 6, 2.70877E – 5)
1.0(2.60940E – 3, 1.01976E – 2)(1.62781E – 4, 6.47543E – 4)

Absolute errors of Application 1 for ψ2(x)_

xMethod in [31] (m=10)Suggested methodSuggested methodSuggested method
|ψExact| – ψTaylor|m=1m=2m=3
0.12.229 × 10−32.17774 × 10−16.77644 × 10−20
0.22.271 × 10−21.12737 × 10−13.64407 × 10−20
0.31.835 × 10−25.73750 × 10−21.80167 × 10−20
0.47.450 × 10−42.69276 × 10−28.04810 × 10−30
0.52.317 × 10−21.03606 × 10−23.20315 × 10−30
0.63.458 × 10−22.43533 × 10−41.17962 × 10−30
0.79.332 × 10−39.73055 × 10−35.69291 × 10−40
0.81.111 × 10−12.60431 × 10−26.88201 × 10−40
0.96.109 × 10−25.64250 × 10−21.39386 × 10−30
1.01.101 × 10−11.10788 × 10−12.91265 × 10−30

Absolute errors of Application 4 by Block-Pulse functions method in [30] for (ψ1(x), ψ2(x))_

xM=16M=32
0.1(7.570 × 10−3, 5.960 × 10−3)(1.124 × 10−2, 8.260 × 10−3)
0.2(2.212 × 10−2, 1.481 × 10−2)(3.560 × 10−3, 2.370 × 10−3)
0.3(2.606 × 10−2, 1.441 × 10−2)(4.390 × 10−3, 2.700 × 10−3)
0.4(8.320 × 10−3, 3.660 × 10−3)(1.406 × 10−2, 6.500 × 10−3)
0.5(5.185 × 10−2, 1.989 × 10−2)(2.572 × 10−2, 9.680 × 10−3)
0.6(1.221 × 10−2, 4.020 × 10−3)(1.699 × 10−2, 4.950 × 10−3)
0.7(3.744 × 10−2, 8.690 × 10−3)(6.060 × 10−3, 1.390 × 10−3)
0.8(4.174 × 10−2, 9.480 × 10−3)(6.440 × 10−3, 7.800 × 10−4)
0.9(1.499 × 10−2, 1.670 × 10−3)(2.309 × 10−2, 4.130 × 10−3)
1.0(8.308 × 10−2, 1.299 × 10−2)(4.217 × 10−2, 6.130 × 10−3)

Absolute errors of Application 3 for ψ1(x)_

xMethod in [30]Method in [30]Suggested methodSuggested method
m=16m=32m=1m=2
0.18.698 × 10−21.980 × 10−32.38200 × 10−10
0.21.898 × 10−23.450 × 10−31.91404 × 10−10
0.31.855 × 10−28.540 × 10−31.49116 × 10−10
0.45.420 × 10−31.210 × 10−21.11397 × 10−10
0.53.123 × 10−21.386 × 10−27.83878 × 10−20
0.68.538 × 10−26.410 × 10−35.03014 × 10−20
0.71.876 × 10−29.140 × 10−32.74219 × 10−20
0.81.877 × 10−21.314 × 10−21.01035 × 10−20
0.96.150 × 10−31.512 × 10−21.22547 × 10−30
1.03.137 × 10−26.860 × 10−36.05633 × 10−30

Absolute errors of Application 1 by BPM and HBBPFM in [41] for (ψ1(x), ψ2(x))_

xBPMHBBPFMHBBPFM
n = 10n=6, M=25n=7, M=14
0.1(3.47 × 10−4, 9.66 × 10−4)(1.34 × 10−4, 1.28 × 10−4)(9.88 × 10−6, 5.60 × 10−6)
0.2(4.78 × 10−4, 8.25 × 10−4)(2.77 × 10−4, 2.95 × 10−4)(7.63 × 10−6, 9.90 × 10−6)
0.3(5.28 × 10−4, 6.35 × 10−4)(4.13 × 10−4, 4.88 × 10−4)(3.65 × 10−6, 9.40 × 10−6)
0.4(7.92 × 10−4, 4.56 × 10−4)(6.75 × 10−5, 9.67 × 10−5)(1.33 × 10−6, 3.50 × 10−6)
0.5(3.68 × 10−4, 1.96 × 10−4)(6.03 × 10−5, 7.36 × 10−5)(6.94 × 10−6, 7.00 × 10−7)
0.6(4.73 × 10−4, 9.25 × 10−4)(2.04 × 10−4, 1.66 × 10−4)(3.77 × 10−6, 1.00 × 10−6)
0.7(3.11 × 10−5, 7.41 × 10−4)(9.25 × 10−5, 3.55 × 10−4)(6.46 × 10−6, 3.70 × 10−6)
0.8(9.43 × 10−5, 3.67 × 10−4)(6.04 × 10−5, 3.56 × 10−4)(8.80 × 10−6, 8.00 × 10−7)
0.9(7.36 × 10−4, 8.93 × 10−4)(3.82 × 10−5, 2.00 × 10−4)(6.14 × 10−6, 5.09 × 10−2)

Absolute errors of Application 2 for ψ1(x)_

xMethod in [26]Suggested methodSuggested method
|ψExactψADM|m=1m=2
0.11.33 × 10−22.40124 × 10−10
0.21.52 × 10−22.18895 × 10−10
0.31.71 × 10−21.90581 × 10−10
0.41.89 × 10−21.57067 × 10−10
0.52.08 × 10−21.20238 × 10−10
0.62.26 × 10−28.19810 × 10−20
0.72.45 × 10−24.41810 × 10−20
0.82.64 × 10−28.72381 × 10−30
0.92.82 × 10−22.25048 × 10−20
1.03.02 × 10−14.76190 × 10−20

Absolute errors of Application 3 for ψ2(x)_

xMethod in [30]Method in [30]Suggested methodSuggested method
m=16m=32m=1m=2
0.15.600 × 10−42.900 × 10−46.62637 × 10−30
0.22.810 × 10−41.720 × 10−36.70369 × 10−30
0.38.230 × 10−31.340 × 10−33.58039 × 10−30
0.41.123 × 10−28.120 × 10−33.55018 × 10−40
0.53.136 × 10−21.409 × 10−23.43149 × 10−30
0.63.171 × 10−22.405 × 10−24.53355 × 10−30
0.72.701 × 10−29.000 × 10−52.99261 × 10−30
0.82.666 × 10−21.795 × 10−21.48519 × 10−30
0.99.855 × 10−34.490 × 10−38.86505 × 10−30
1.02.900 × 10−22.900 × 10−41.88099 × 10−20

Absolute errors of Application 4 for ψ2(x)_

xm=1m=2m=3m=4
0.15.08674 × 10−29.01505 × 10−21.27633 × 10−36.45456 × 10−3
0.25.50850 × 10−26.80369 × 10−21.68664 × 10−42.04838 × 10−3
0.35.35456 × 10−24.97035 × 10−24.25853 × 10−41.32564 × 10−3
0.44.75126 × 10−23.47864 × 10−26.56463 × 10−48.12332 × 10−4
0.53.80803 × 10−22.29547 × 10−26.50718 × 10−44.62022 × 10−4
0.62.61641 × 10−21.39002 × 10−25.13929 × 10−42.36744 × 10−4
0.71.24855 × 10−27.32388 × 10−33.29481 × 10−41.03630 × 10−4
0.82.45176 × 10−32.92136 × 10−31.59256 × 10−43.45574 × 10−5
0.91.84003 × 10−23.64138 × 10−44.44145 × 10−56.15417 × 10−6
1.03.54318 × 10−27.23693 × 10−46.92641 × 10−69.48343 × 10−8

Absolute errors of Application 5 by Taylor-series expansion method in [31] with m = 10_

xψ1(x)ψ2(x)
0.13.809 × 10−26.406 × 10−3
0.22.748 × 10−24.259 × 10−3
0.31.745 × 10−24.240 × 10−4
0.48.999 × 10−32.835 × 10−3
0.52.914 × 10−33.644 × 10−3
0.63.770 × 10−45.120 × 10−4
0.79.700 × 10−47.755 × 10−3
0.83.290 × 10−42.216 × 10−2
0.91.818 × 10−34.367 × 10−2
1.07.100 × 10−47.329 × 10−2

Absolute errors of Application 2 by B-spline wavelet method in [40] for (ψ1 (x), ψ2(x))_

xM=2M=4
0.1(2.22045E – 16, 1.04167E – 4)(4.44089E – 16, 6.51042E – 6)
0.2(0.00000000000, 1.14583E – 3)(2.22045E – 16, 7.16146E – 5)
0.3(2.22045E – 16, 1.14583E – 3)(2.22045E – 16, 7.16146E – 5)
0.4(2.22045E – 16, 1.04167E – 4)(4.44089E – 16, 6.51042E – 6)
0.5(4.44089E – 16, 2.60417E – 3)(1.33227E – 16, 1.62760E – 4)
0.6(2.22045E – 16, 1.04167E – 4)(6.66134E – 16, 6.51042E – 6)
0.7(6.66134E – 16, 1.14583E – 3)(4.44089E – 16, 7.16146E – 5)
0.8(4.44089E – 16, 1.14583E – 3)(4.44089E – 16, 7.16146E – 5)
0.9(4.44089E – 16, 1.04167E – 4)(6.66134E – 16, 6.51042E – 6)
1.0(6.66134E – 16, 2.60417E – 3)(8.88178E – 16, 1.62760E – 4)

Absolute errors of Application 4 by rationalized Haar functions method in [28] for (ψ1(x), ψ2(x))_

xM=16M=32
0.1(7.970 × 10−3, 5.950 × 10−3)(1.014 × 10−2, 8.370 × 10−3)
0.2(2.203 × 10−2, 1.490 × 10−2)(3.550 × 10−3, 2.480 × 10−3)
0.3(2.615 × 10−2, 1.436 × 10−2)(4.480 × 10−3, 2.410 × 10−3)
0.4(8.310 × 10−3, 3.790 × 10−3)(1.418 × 10−2, 6.410 × 10−3)
0.5(5.175 × 10−2, 1.968 × 10−2)(2.582 × 10−2, 9.660 × 10−3)
0.6(1.231 × 10−2, 3.950 × 10−3)(1.693 × 10−2, 4.990 × 10−3)
0.7(3.724 × 10−2, 8.610 × 10−3)(6.070 × 10−3, 1.410 × 10−3)
0.8(4.214 × 10−2, 9.200 × 10−2)(7.140 × 10−3, 1.590 × 10−3)
0.9(1.478 × 10−3, 1.690 × 10−3)(2.492 × 10−2, 4.030 × 10−3)
1.0(8.418 × 10−2, 1.261 × 10−2)(4.227 × 10−2, 6.030 × 10−3)
Language: English
Submitted on: Dec 30, 2024
|
Accepted on: Aug 30, 2025
|
Published on: Jan 29, 2026
Published by: Harran University
In partnership with: Paradigm Publishing Services
Publication frequency: 2 issues per year

© 2026 Mohsen Didgar, Farzan Ekhlasi, published by Harran University
This work is licensed under the Creative Commons Attribution 4.0 License.

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