Abstract

You can exploit your current knowledge of Excel's formula language to build customized Excel functions. These user-defined functions are so fast and transparent that they may be useful for validating AI answers or replacing them altogether. You can now use loops that previously required VBA or JavaScript. The functions use Excel's new =LAMBDA and =MAKEARRAY functions. You can assign personalized names to functions and their input variables, and they are portable between Workbooks. We present simple examples showing basic syntax, building up to a compact fixed income example: a user-defined function using a Taylor series to estimate the change in a bond's price given a given change in yield-to-maturity, where you choose how many terms of the Taylor series to include.

Document Type

Working Paper

Publication Date

6-25-2026

Publisher Statement

Please do not cite without permission.

Click below to download supplemental content.

TAYLOR-LAMBDA-ARNOLD-CRACK-2.xlsx (25 kB)

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