In: Advanced Math
Evaluate the integral of f(x) below between x=1.5 and x=5.3 using Gauss-Legendre formulas for 2, 3, and 4 points.
Compare with analytical integration, calculate the % error of the numerical method.
f(x)=4+8x−21x2 +16x3 −5x4 +7x5
The values above calculations are obtained using Excel. The intermediate calculations are as follow
t | 3.4+1.9t | (3.4+1.9t)^2 | (3.4+1.9t)^3 | (3.4+1.9t)^4 | (3.4+1.9t)^5 | f(3.4+1.9t) | Coefficients | f(3.4+1.9t)*coefficients |
-0.5773502 | 2.303035 | 5.303968461 | 12.21522299 | 28.13208143 | 64.78915748 | 419.3482 | 1 | 419.3482023 |
0.5773502 | 4.496965 | 20.22269763 | 90.94077113 | 408.9574994 | 1839.067717 | 11899.04 | 1 | 11899.03793 |
-0.7745966 | 1.928266 | 3.718211541 | 7.169702605 | 13.82509706 | 26.65847097 | 173.5427 | 0.5555555 | 96.41262508 |
0 | 3.4 | 11.56 | 39.304 | 133.6336 | 454.35424 | 2929.616 | 0.8888888 | 2604.102566 |
0.7745966 | 4.871734 | 23.73378768 | 115.6246895 | 563.2926779 | 2744.211832 | 17787.58 | 0.5555555 | 9881.987229 |
-0.8611363 | 1.763841 | 3.111135179 | 5.487547879 | 9.679162103 | 17.07250325 | 111.6894 | 0.3478584 | 38.85208478 |
-0.339981 | 2.754036 | 7.58471484 | 20.88857848 | 57.52789921 | 158.4339112 | 1022.368 | 0.6521451 | 666.7325522 |
0.339981 | 4.045964 | 16.36982388 | 66.23171647 | 267.9711339 | 1084.201534 | 7001.864 | 0.652145 | 4566.23056 |
0.8611363 | 5.036159 | 25.36289717 | 127.7315821 | 643.2765529 | 3239.642982 | 21016.49 | 0.347858 | 7310.754824 |
Hello!
I hope you will understand the answer.
If you have any doubt, let me know by comment i will respond.
The table included for reference.