\( N \) | Trapez | Simpson | Gauss-Legendre |
10 | 1.821020 | 1.214025 | 0.1460448 |
20 | 0.912678 | 0.609897 | 0.2178091 |
40 | 0.478456 | 0.333714 | 0.2193834 |
100 | 0.273724 | 0.231290 | 0.2193839 |
1000 | 0.219984 | 0.219387 | 0.2193839 |
We note here that, since the area over where we integrate is rather large and the integrand goes slowly to zero for large values of \( x \), both the trapezoidal rule and Simpson's method need quite many points in order to approach the Gauss-Legendre method. This integrand demonstrates clearly the strength of the Gauss-Legendre method (and other GQ methods as well), viz., few points are needed in order to achieve a very high precision.