Mathematically, this means that if you draw a curve with torque on one axis versus time on the other axis, and took the first derivative of that curve with respect to time, you would get the horsepower at that instant in time
Darn - made a small boo-boo. If you draw a curve with torque on one axis versus time on the other axis, and took the first derivative of that curve with respect to time, you'd get a continuous horsepower curve, over the same length of time. Sorry about that.
Kevin