Numerical Integral

A little more caution should be exercised here than with my other scripts. Your browser may become unresponsive if you use this for a very complicated calculation. Also, I've left out the usual error-checking routines to give the user a little more freedom and power. As a result, it will not catch you if you give it input like "Banana" (Just hit refresh to reset the script, in case you actually tried that).
Expression:
Lower bound:
Upper bound:
Delta:
Answer ≈