docs: add comment, revert to previous tolerance in math/base/special/factorialln

PR-URL: stdlib-js#2778

Reviewed-by: Philipp Burckhardt <pburckhardt@outlook.com>

Author: gunjjoshi

lib/node_modules/@stdlib/math/base/special/factorialln/test/test.js

@@ -143,7 +143,7 @@ tape( 'the function evaluates the natural logarithm of the factorial of `x` (med
 			t.equal( y, expected[i], 'x: '+x[i]+', y: '+y+', expected: '+expected[i] );
 		} else {
 			delta = abs( y - expected[i] );
-			tol = 1.5 * EPS * abs( expected[i] );
+			tol = EPS * abs( expected[i] );
 			t.equal( delta <= tol, true, 'within tolerance. x: '+x[i]+'. y: '+y+'. E: '+expected[i]+'. Δ: '+delta+'. Tolerance: '+tol+'.' );
 		}
 	}

lib/node_modules/@stdlib/math/base/special/factorialln/test/test.native.js

@@ -152,6 +152,8 @@ tape( 'the function evaluates the natural logarithm of the factorial of `x` (med
 			t.equal( y, expected[i], 'x: '+x[i]+', y: '+y+', expected: '+expected[i] );
 		} else {
 			delta = abs( y - expected[i] );
+
+			// NOTE: the tolerance here is larger than for the JavaScript implementation due to compiler optimizations which may be performed resulting in result divergence. For discussion, see https://github.com/stdlib-js/stdlib/pull/2774#discussion_r1712904184
 			tol = 1.5 * EPS * abs( expected[i] );
 			t.equal( delta <= tol, true, 'within tolerance. x: '+x[i]+'. y: '+y+'. E: '+expected[i]+'. Δ: '+delta+'. Tolerance: '+tol+'.' );
 		}