CHKDER Program									02-12-2000
by: Bill Kennedy
bk2001@hotmail.com

The purpose of this program is to verify that one equation (Y2) is a derivative of the other (Y1).  One way to do this is to 2nd calc, 6 (dy/dx) and find a point and hit enter.  Then hit an up arrow or down arrow to jump to the other graph (derivative) and the Y value should agree with the dy/dx value.  But, you have to memorize the dy/dx value to check against the other.  So, I came up with this program to display both numbers at the same time on the screen.  It executes very quickly with minimum keystrokes.  I made 'x' a variable because some functions only work over a limited domain, so an error would be generated if this happens.

This program assumes that an equation has been entered in Y1 and what you think is the derivative of that equation is entered as Y2.  When the program is started, it prompts for an x value.  This value will used to evaluate the derivative of Y1 at this point and evaluate Y2 also.  It will then display "Y1'=" and the result. The next line will display "Y2=" and it's result.  These two results should very closely agree (depending on what the tolerance is set to), if not, exactly agree.  This will mean that Y2 is a derivative of Y1.  The next line displayed is the difference of Y1 and Y2.


This was a quick hack while doing homework (calcII).  If anyone improves on it or finds errors, please email me, and maybe send a copy of the new version.

Happy Calc'n!!