Everybody knows the following image from heart monitors at the hospital, but can you make a function $f(x)$ that models it?
It seems like a combination of linear equations should do the trick, but not just any group of linear equations. There must be the distinct sharpness at the peak of the beat, and some are curved.
Can you find some function $f(x)$ with parameters that models these well known graphs? (it'd be really nice if it could include things like the heart rate and heart pressure (note that situations like stress or near death would preferably be included, as a stress parameter).
As per quid, it appears someone has already asked this question on the math overflow site.