Linear Interpolation Between Two Known Points
If the two known points are given by the coordinates and, the linear interpolant is the straight line between these points. For a value x in the interval, the value y along the straight line is given from the equation
which can be derived geometrically from the figure on the right. It is a special case of polynomial interpolation with n = 1.
Solving this equation for y, which is the unknown value at x, gives
which is the formula for linear interpolation in the interval . Outside this interval, the formula is identical to linear extrapolation.
This formula can also be understood as a weighted average. The weights are inversely related to the distance from the end points to the unknown point; the closer point has more influence than the farther point. Thus, the weights are and, which are normalized distances between the unknown point and each of the end points.
Read more about this topic: Linear Interpolation
Famous quotes containing the word points:
“There are good points about all such wars. People forget self. The virtues of magnanimity, courage, patriotism, etc., etc., are called into life. People are more generous, more sympathetic, better, than when engaged in the more selfish pursuits of peace.”
—Rutherford Birchard Hayes (1822–1893)