Questions tagged [interpolation]

Questions on interpolation, the estimation of the value of a function from given input, based on the values of the function at known points. It is necessary because in science and engineering we often need to deal with discrete experimental data.

Interpolation is a useful mathematical and statistical tool used to estimate values between two points on a line or curve.

What Is Interpolation?

Interpolation is the process of deriving a simple function from a set of discrete data points so that the function passes through all the given data points (i.e. reproduces the data points exactly) and can be used to estimate data points in-between the given ones.

To help us remember what it means, we should think of the first part of the word, 'inter,' as meaning 'enter,' which reminds us to look 'inside' the data we originally had.

Applications: This tool, interpolation, is not only useful in statistics, but is also useful in science, business or any time there is a need to predict values that fall within two existing data points. It is also used to simplify complicated functions by sampling data points and interpolating them using a simpler function. In the mathematical field of numerical analysis, interpolation is a method of constructing new data points within the range of a discrete set of known data points. In engineering and science, one often has a number of data points, obtained by sampling or experimentation, which represent the values of a function for a limited number of values of the independent variable. It is often required to interpolate, i.e., estimate the value of that function for an intermediate value of the independent variable.

The details, techniques, and precise meaning of interpolation depend heavily on the sub-discipline of mathematics, therefore you are encouraged to use additional subject tags such as , , , or when appropriate.

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Vector/Multidimensional version of Newton Divided Difference

newton divided difference polynomial (NDDP) finds an y=f(x) relation by interpolating a polynomial, is there a y=f(x,z) version for n dimensions? Any help appreciated.
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Find an equation fitting a set of points

In a game that I play, there is a power value that is an overall evaluation on how powerful your account is. There is a function where you can level up a skill, and levelling it up gives a bonus to your power rating. With help, I found exactly how…
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Is there an equation for the exact line of best fit?

Is there some sort of equation/formula that can be used to find the exact values of $m$ and $b$ in $y=mx+b$ of any data points for the line of best fit? I want to be able to do this manually, not with graphing tools. I know with $2$ points,…
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Polynomial regression interpolation?

Possible Duplicate: Writing a function $f$ when $x$ and $f(x)$ are known I'm not versed in mathematics, so you'll have to speak slowly... If I want to fit a curve to the points, X Y 1 0.5 2 5.0 3 0.5 4 2.5 5 5.0 6 0.5 Where would I begin?…
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Curve fitting for 2D Data and Interpolation

I have polygon with $n$ Corner points where stresses are known to me. I have to fit a sutface $F(x,y)$, which can give the value of stress at anypoint inside the polygon. I fitted a curve using a polynomial with $n$ terms. The fitted curve exactly…
prem
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How to use bilinear interpolation?

I need an explanation about Bilinear Interpolation. I use KNN and find $4$ points which I need to use bilinear interpolation to find unknown position. I was unable to understand explanations in other sites. I need to write equations for $x$ and $y$…
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Formula for $N$-Dimensional linear interpolation

Linear interpolation between values $A$ and $B$ can be defined as: $f(x) = A(1-x)+Bx$ Bilinear interpolation between values $A,B,C,D$ is defined as: $f(x,y) = g(x)(1-y) + h(x)y$ where $g(x) = A(1-x)+Bx$ and $h(x) = C(1-x)+Dx$ So, bilinear…
Alan Wolfe
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How can I characterise the error of an interpolated surface?

I am writing a program in which I can interpolate and display a surface by kernel interpolation. Lets say I interpolate a function $f(x)$ by the function $f^*(x)$. Clearly the error at any given point is merely $|f(x) - f^*(x)|$, but how can I…
j x
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Continuously differentiable interpolation

I have real values $y_i$ given on uniform grid. I want to build interpolating function $f(x)$ such that: $f(x) = y_i$, when $x=i$, $f$ is continuously differentiable. Instead of using famous cubic-splines, I would like to find a technique meeting…
0x2207
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Given an interpolating polynomial, how do I find another polynomial that interpolates at 1 less point?

The polynomial $$p(x) = x^5-2x^4-5x^3+15x^2+4x-12$$ interpolates x = -2,-1,1,2,3,0 with p(x) = f1, f2, f3, f4, f5, -12 respectively. In general, how do I find another polynomial of a lower degree that interpolates at all points except the last one…
aveiur
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What interpolation method makes the fewest assumptions about the function?

If I have no information about a function except a regular timeseries of samples, what is theoretically the best interpolation method to use and why? We cannot assume the function is continuous etc. I said no other information. Which interpolation…
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Using linear interpolation between two points to find the three remaining points

I am taking a graphics programming course, and I am looking at how Linear interpolation can be used to move points from one location to another location within a certain time. My mathematics background information is poor, so can someone explain…
Moynzy
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Need help showing piecewise cubic $Z(x,y)$ is $C^1$

We work in $\mathbb{R}^2$. Given a non-degenerate triangle $\triangle ABC$ and an interior point $P$, we specify the value of a function, value of its gradient at the $A,B,C$, and we specify the normal derivative at the midpoints of the vertices. I…
nullUser
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Getting error of interpolating polynomial by subtraction.

$f(x)= \frac{1}{1+x^2}$ and when I computed the interpolating polynomial of 5 equally spaced points in [-5,5] I got $ p(x)= 0.0053x^4 -0.1711x^2 +1$ Now I need to estimate the error in the interpolant using the error…
S.Dan
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computing interpolating polynomials of 5 equally spaced points in a given interval

The question I faced is as follows:- Consider Runge's function. $f(x)= \frac{1}{1+x^2}$ Compute and graph the interpolating polynomials (atop a graph of Runge's function itself) of with 5 equally spaced points in the interval [-5,5]. Does this mean…
S.Dan
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