Linear and Quadratic Interpolation

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Linear Interpolation Diagram
Berland. Based on png-version Image:Linear_interpolation.png. Newer version by ElectroKid (☮ • ✍), Public domain, via Wikimedia Commons

Interpolation is a common engineering task that allows quick estimates to be made using existing data. Examples include estimating values between rows of a table or estimating how a parameter will change based on a couple of simulation runs. The first sheet below performs linear interpolation between two points: (x1, y1) and (x2, y2). The second sheet performs quadratic interpolation using a parabola defined by three points: (x1, y1), (x2, y2) and (x3, y3). Both of the sheets are currently setup to not use units. However, units can be easily added to each sheet using the row in the table below the variable names. If units are defined for the x values, than the x value in the last cell needs to have a unit defined as well to keep the units consistent. Additional rows can be added to the first table in either of the sheets to provide an easy way to quickly switch between multiple scenarios. The linear interpolation and quadratic interpolation sheets can also be opened in separate windows. 

Linear and Quadratic Interpolation
by u/mgreminger in EngineeringPaperXYZ

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