The interpolation method is a method that allows you to find intermediate values of a value from an existing discrete set of known values.

x_{1}

**x** (между х_{1 }и х_{2})

x_{2}

y_{1}

f(x_{1, }y_{1})

f(x_{2, }y_{1})

y (между y_{1 }и y_{2})

y_{2}

f(x_{1, }y_{2})

f(x_{2, }y_{2})

In this online calculator, double linear interpolation is performed for the function f (x, y), if the value of x is in the interval between x_{1} and x_{2}, y is in the interval between y_{1} and y_{2} and the values of the function f (x_{1}), f (x_{2}) are known, f (y_{1}), f (y_{2})

Therefore, the interpolation formula has the following form:

At the beginning we find: f(x,y_{1})= (f(x_{2},y_{1})-f(x_{1},y_{1}))/(x_{2}-x_{1})*(x-x_{1})+f(x_{1},y_{1}),

and then we find: f(x,y_{2})= (f(x_{2},y_{2})-f(x_{1},y_{2}))/(x_{2}-x_{1})*(x-x_{1})+f(x_{1},y_{2}),

and then we find **f(x,y)**= (f(x,y_{2})-f(x,y_{1}))/(y_{2}-y_{1})*(y-y_{1})+f(x,y_{1}),