by James W. Walker
12 September 2009
During a budget crisis in the summer of 2009, the State of California began paying debts using "registered warrants" (colloquially known as IOUs). Unlike checks, these could not be cashed immediately, but earned interest from the date of issue to the date when they became redeemable, namely 4 September 2009.
The state office of the Controller posted a web page titled Registered Warrants Interest Calculator Page. You might think that this would allow you to calculate the interest right there on the page, but no, it provided a download link to a Microsoft Excel spreadsheet. And what if you didn't have Excel? They provided a link to a Microsoft page where one could download a free Excel Viewer program. There's one slight catch: Excel Viewer is only available for Windows. Being a Mac user from way back, I found this irritating.
I wondered how hard it would have been to whip up a web page with some JavaScript to compute the interest. After all, we're not talking about multivariate calculus here*. You just have to figure out how many days the registered warrant was earning interest, multiply by the face amount and the daily interest rate, and you're done. I had no previous experience with Javascript programming, so it took me a few days, but here it is.
You just need to type in the date of issue and the face amount. There's no "calculate now" button. Every time you type in one of the fields, the script checks whether it has enough information to do the calculation.
Issue Date (mm/dd/yy):
Days of interest:
(If the number of days remains blank, then you haven't yet typed in the full date in the right format.)
Dollar amount of registered warrant: $
Calculated interest: $
* I considered saying "we're not talking about sheaf cohomology here", but I wasn't sure readers would recognize that as math.