When making an equation curve in a 2d sketch, you should not have to manually figure out the units and correct for them. There should be a checkbox to make y default to the same unit as x.
Right now, to create the curve, y=x^2, when x is in inches, you have to type:
y=x^2/1in
The isolate function should also work here, but it does not:
isolate(x^2;in^2;in)
The above equation only works in the parameters editor.
Also, try quickly typing "x^2/1in" into the y(x) box of an explicit 2d equation curve. It will "auto-correct" to "x^2in"
It you pause for a second after typing the 1, it will let you finish typing it correctly.
