reverse engineering a graph
I have a graph with multiple curved lines on it that I am supposed to use a "graphic interpolator" (straight edge) in determining a value. The curved lines represent temperature in Celsius, the Yaxis is pressure altitude and the XAxis is Torque represented as a percent. Based on my Pressure Altitude and the current Temperature, I follow the Y axis and the curved line to find their intersection, and at that point on the X axis I would find my maximum allowable torque for that parameter. My question is this:
If I know the X,Y coordinates (3 or more) of where the curved line intersects the X and Y axes, can I determine and write an algorithm to solve for X? basically drawing the curved line programmatically? The graph is already made, but printed on a sheet of paper in a xeroxed handout and I want to get it into a digital system for faster calculations.
Thanks in advance for any help...
