Excel doesn't really know how to create a function plot. It generally needs you to create a table of data, that can then be plotted. However, thanks to the use of array functions, named ranges, the old excel evaluate function, and some tweaking (as described in an informit article by Rob Bovey, Stephen Bullen, and John Green), I was able to create a plotter for formulas that doesn't need any data or any VBA.
Here's the first one, generated from these parameters
y= (SQRT(COS(x))*COS(200 *x)+SQRT(ABS(x))-0.7)*(4-x*x)^0.01 x from -1.57 x to 1.57 no of points 10000