This custom 2-dimensional linear interpolation function, =Linterp () *, accepts 3 arguments: =Linterp (KnownYs, KnownXs, NewX) The order of the arguments is the same as in the Excel worksheet function =TREND (). The above formula is the Linear Interpolation Formula. Function Linterp2 (rX As Range, rY As Range, x As Double) As Double ' linear interpolator / extrapolator ' R is a two-column range containing known x, known y Dim lR As Long, l1 As Long, l2 As Long Dim nR As Long 'If x = 1. Basically, the Excel formula is simple: =_X1+ (_X2 – _X1)* (Y – _Y1)/ (_Y2 – _Y1) Linear Interpolation [/captionThis formula can be written in a more familiar style, the relationship between the known points ( X1,Y1) and ( X2,Y2) and unknown location of X, Y is: For the below data table, the problem is that finding the _X1, _X2 and. See the yellow-highlighted cells in my "corrected" sheet in the attached Excel file. We will show you 2 ways. Basically, the Excel formula is simple: =_X1+ (_X2 – _X1)* (Y – _Y1)/ (_Y2 – _Y1) Linear Interpolation [/captionThis formula can be written in a more familiar style, the relationship between the known points ( X1,Y1) and ( X2,Y2) and unknown location of X, Y is: For the below data table, the problem is that finding the _X1, _X2 and. You can also use Excel to calculate a regression with a formula that uses an exponent for x different from 1, e. Refer to the image below. It fits a straight line (using the method of least squares) to the array's known_y's and known_x's. Bilinear interpolation - VBA code to be put in a module. The formula in B17 is:2 – Convert your Data into a Table. need an excel simple formula or function that returns values of y for given x in a two-dimensional array and works in the following way. Piecewise linear interpolation Figure 3. Use Mathematical Formula to Calculate Logarithmic Interpolation in Excel. Target date can be date/time or numeric. It is easy to perform interpolation of non-linear 2D data in Excel. 6. So E8 will lie between 3 and 4, based on the. If the known data is contiguous, with the points to be interpolated elsewhere on the sheet, you could use the FORECAST() function for linear interpolation. > spreadsheets like Quattro Pro do). We will show you 2 ways. Introduction. Then, insert two columns named LogX. I would like to write an Excel function that linearly interpolates between data points. The case is best illustrated in the attached sheet. Step 2: Input Required Data into Cubic Spline Model. You can use interpolation to fill-in missing data, smooth existing data, make predictions, and more. This is the lower value for interpolation. Count <> YRates. The data is set up as follows. 56 5Y 0. if x=1. You can use these functions to predict future sales, inventory requirements, or consumer trends. “X” is the first set of values, and “Y” is the second set of values. Question: Find the value of y at x = 4 given some set of values (2, 4), (6, 7)? Solution: Given the known values are, x = 4 ; x 1 = 2 ; x 2 = 6 ; y 1 = 4 ; y 2 = 7. . Interpolation is a method used to determine a present or future value factor when the. If you're stuck working in Excel. To execute a linear interpolation in Excel, we use the forecast function and the lookup function to create a straight line that connects two values and estimates the future value through it. The next two parameters, known_y_pair and known_x_pair are the values either side of NewX. The position of the median. [Edit]: You will need to sort your arrays on the x axis as @ImportanceOfBeingErnest adds. richthorpe, this post is unlikely to be very useful for your purposes, but you may get some interest from it. Utilize Fill Command to Interpolate Time Series in Excel. With optional arguments, you can control the interpolating spline properties. The N-1 Basis method is used by Excel’s legacy QUARTILE function and by the QUARTILE. Linear Interpolation. docx. S, S’, S” are all continuous function on [a, b]. This tip explains how to use the function. Hello, I am trying to get an excel formula that will do linear interpolation for me. 5) using OFFSETs to select the square of that line and the next (in light purple) using FORECAST to build a linear interpolation using just those two points, and getting the resultOn the off chance that we leave the Type as Linear, Excel will utilize the accompanying equation to figure out what step is worth using to fill in the missing information: Step = (End – Start)/ (#Missing obs + 1) For this model, it decides the step worth to be: (34 – 21)/ (4 + 1) = 2. Interpolate Excel Formula. The following Microsoft Excel formula performs linear interpolation by calculating the interpolation. Line 5 gives us the higher value for interpolation: 5: MINIFS(B:B,B:B,">" &VLOOKUP(D5, A:B, 2, TRUE)) It searches column B for the smallest value (using the MINIFS function) but applies the condition that the smallest value should be larger than the value found by the lookup in line 4. xla, delete it, save the new file and seek. Interpolation Logarithmic Logarithmic scale Plots Scale. Use the following Formula in the cell I2 to interpolate for the value 0. Now, we can see a new sidebar named ‘ Format Trendline ’. Linear interpolation is a common method used in Excel to estimate a missing value or to interpolate a value between two existing data points. Once you click on Data Analysis, a new window will pop up. 1. linear(a2,c2:d2,e2:f2),na())which is the formula for linear interpolation in the interval (,). Description. Step 5: Display Chart Data for Cubic Spline Interpolation in Excel. First, you need the data graph so Excel can fit a line to the data and g. Function LinInterpolation(DataX As Range, DataY As Range, point As Range) As Variant: If point. Add input cells for height and span in J1 and J2 respectively. “X” is the first set of values, and “Y” is the second set of values. Step 4: Determine Interpolate Y Value Using User-Defined Function in Excel. Excel has a standard worksheet function, forecast, which you can use for interpolation. g. Excel Formulas & Functions. LINEAR Result: GROWTH Result: FORECAST Inner-linear interpolation (manual) FORECAST Inner-linear interpolation (automatic) Author: Excel Off The Grid Last modified by: Mark Proctor Created Date: 4/8/2020 7:55:27 PM Other titles:Formula to Extrapolate in Excel. To begin, we will type in the function name “ =BicubicInterpolation ( “. --. t0 = 15, v(t0) = 362. Copy the value in C1 and paste it in cell B4 to replace the missing value. Interpolation is the process of estimating an unknown value of a function between two known values. If we leave the Type as Linear, Excel will use the following formula to determine what step value to use to fill in the missing data: Step = (End – Start) / (#Missing obs + 1) For this example, it determines the step value to be: (35-20) / (4+1) = 3. S. Use this value in the INDEX function to return the values of jc0, y0, and^i, as shown in the. We can calculate the Interpolate mathematically using the formula, y = y1 + (x – x1) ⨯ (y2 – y1) / (x2 – x1). That formula is: The equation y = y1 (x – x1) (y2 – y1) / (x2 – x1) All of the values used in this formula—x1, x2, y1 and y2—are known. To interpolate this value, use the following simple formula: (x – x1) * y= y1 + (x – x1) x=22. Linear-Interpolation Method. Genius, try Googling linear+interpolation+using+excel+formula Top 2 results: 1 indeed: How To Perform Linear Interpolation in Microsoft Excel and 2 Engineerexcel: Linear Interpolation in Excel. linear interpolation, which assumes developmentproportional to time over the period. #6. In summary, linear interpolation can be used to find y for a known x on a linear scale plot, using the formula y = y1 + (x-x1) (y2-y1)/ (x2-x1). In numerical analysis, multivariate interpolation is interpolation on functions of more than one variable ( multivariate functions ); when the variates are spatial coordinates, it is also known as spatial interpolation . Steps: Determine which value you want to interpolate and make new rows for the value you want to interpolate and the interpolated In this case I want to interpolate. Shorthand for linear interpolation, you can imagine lerp as a way to “blend” or “move” between two objects, such as points, colours and even angles. For linear interpolation have the sheet active and run the following. You just need to insert the formula. In Excel 2016, the FORECAST function. We can add another series to highlight the input data points. Interpolation. Value 'Get. You can visualize it by plotting the points in a scatterplot and generate a trendline. LINEAR must be changed to =FORECAST (depreciated soon). Linear interpolation on a data set (red points) consists of pieces of linear interpolants (blue lines). I had to use multiple "Match" and "Index" Method to do the "linear interpolation" for myself. Thanks for the reply, Herbds7. xll. Then right click on the data series and select “Add Trendline…”. . The survey data consists of type 1 data taken at stations of known locations (X and Y coordinates) along a line (flagged physically in the field), and type 2 data collected every 0. Remember that likely none of us on this side of the internet has done this sort of calculation. You have to use it as native function of Google Sheet 1. Given (x1, y1) and (x2, y2), we can estimate the y-value for a given x-coordinate. 4 when we asked for the 80 th percentile earlier?FORECAST. ETS (target_date, values, timeline, [seasonality], [data_completion], [aggregation]) The FORECAST. Bilinear interpolation - VBA code to be put in a module. Hussein K. As the name implies it fits a straight line to each. This is the lower value for interpolation. Hi All, I've recently come across a formula for interpolation which can be seen in the screenshot below. Linear Interpolation Formula is the process of finding a value between two points on a line or curve. If the points in the data set change by a large amount, linear interpolation may not give a good estimate. + b n x n + a. That. LINEAR(X,knownY,knownX) function. Treasury Bond Yield Curve R Corner - Creating Historical Portfolios Recommended Application: Instapaper Number Puzzle October Number Puzzle Solutions NONLINEAR INTERPOLATION WITH EXCEL TO CONSTRUCT U. Writing user defined Interpolation function in Excel. This browser is no longer supported. For the "Value III" I know the math formula when you interpolate r numbers between two numbers a and b then the distance d between interpolated numbers is: d = (b-a)/ (r+1) And the values of those interpolated numbers are: r1 = a + d r2 = r1 + d or r2 = a + 2*d r3 = r2 + d or r3 = a + 3*d. Given an X vector, this function interpolates a vector Y based on the input curve (XY Range). First, the value of x will go, then add the y-axis values and finally add x-axis values in the formula and click Enter. Linear regression is one of the most common methods of extrapolation in Excel and involves fitting a straight line to the data. Treasury Bond Yield Curve R Corner - Creating Historical Portfolios Recommended Application: Instapaper Number Puzzle October Number Puzzle Solutions NONLINEAR INTERPOLATION WITH EXCEL TO CONSTRUCT U. Select the column of y-values in the same table and name those “yvalues”. In this formula, (x1, y1) is referring to the first coordinate of the interpolation process. Verma @ 1 person found this reply helpful. Beispiel: Lineare Interpolation in Excel. The correct formula to use is of the form: =IFERROR. In this case, F7=7 and E7=3 because B already included the integer 7 and has a matching value in column A. You could change the Forcast line to: Sheets (1). 66, 5+3. I assume that you want linear interpolation between 2 x values. – Scott Craner. Calculate, or predict, a future value by using existing values. Next, select all the air velocity numbers (cells D7-L15) and name them “zvalues”. which is halfway through the median interval, as it should be: I deliberately made the example really simple (and symmetric). g. We’ve added the value 0. See full list on engineerexcel. e. Line 5 gives us the higher value for interpolation: 5: MINIFS(B:B,B:B,">" &VLOOKUP(D5, A:B, 2, TRUE)) It searches. Example: Linear Interpolation in Excel: Consider the following dataset in Excel: Linear Interpolation in Excel. etc. 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. Hi. The symbols N (P) and N (Py) will denote the norms of P and Py. The dataset that we are going to use has this linear pattern, although it has some of its data missing, as seen in the image. Cells. Also, the linear interpolation formula is a method that is useful for curve fitting using linear polynomials. Linear Interpolation - Key takeaways. For example, A3=3 and B3=7. We seek to find the Y value for an arbitrary X value between these two points, such that it is on the straight line that is drawn between them. HTH, Bernie MS Excel MVP Function Interpolate(Xnow As Double, _ XRates As Range, YRates As Range) As Double Application. The new data points are located using the interpolation approach inside the bounds of a discrete set of existing. So the formula for linear interpolation is y = y1 + (x-x1) (y2-y1)/ (x2-x1). In reply to Day William's post on August 3, 2022. Right-click on one of the data points in the chart and select Add Trendline. Image: Bilinear interpolation – axes and map representation. Multiple regression equation: y = b 1 x 1 + b 2 x 2 +. Click on DATA along the top ribbon, then click the Data Analysis option on the far right. There are a few different types of interpolation techniques. The following Microsoft Excel formula performs linear interpolation by calculating the interpolation step value: =(end-start)/(ROW(end)-ROW(start)) where end. First row and column must be sorted in ascending or descending order (see following picture). But in excel I don't even know where to start, maybe. This uses Excel Forecast function =FORECAST (x,known_y's,known_x's). Introduces a method to calculate interpolation step value in Excel. Interpolation in Excel based on Splines and Natural Neighbor Algorithm 2D (Curve) Interpolation Use INTERPXY to: Interpolate from a set of (x,y) data points. In MS Excel, press Alt+F11 to open the Visual Basic Editor (Windows). That is, it is recalculated every time any cell in any worksheet in the workbook is edited, as well as after certain other operations. Then. Declaring. forcast wants a range or an array and not numbers which is what you are passing with indexys:indexys1 You are passing the values of the index, so it would return something like 104:34 and not a range or an array. Follow. Using the Trendline, Excel can fit exponential, logarithmi. Polynomial. Do Interpolation of Non-Linear 2D Data in Excel. You will use the FORECAST function when you need a function to forecast your data without making charts and graphs. The existing values are known x-values and y-values, and the future value is predicted by using linear regression. Function for linear interpolation and extrapolation with double entrance in first row and first column. The GROWTH function in Excel allows us to interpolate data when the data set has exponential growth. Linear Interpolation - Key takeaways. The objective is to replace #N/A errors in a data vector (figure 1 top panel) with formulas returning the interpolated value (figure 1 bottom panel). If you extrapolate based on x much, much less than x_list[0] or x much, much greater than x_list[-1] , your return result could be outside of the range of. ----- Pairwise linear interpolation is demonstrated in B17 and B18. There are various ways to interpolate: spline, polynomial, linear and so on. Excel Linear Interpolation Linear interpolation in excel means forecasting or guessing the upcoming next value of any certain variable given on the. For example, you’d use the 11 o’clock measurement as an estimate from 10:30 to 11:30, then you’d use the 12 o’clock. Table of Contents hide. Given two known values (x 1, y 1) and (x 2, y 2), we can estimate the y-value for some point x by using the following formula:. Bei der Interpolation wird ein unbekannter Wert einer Funktion zwischen zwei bekannten Werten geschätzt. You'll need much more advanced software for that, such as MatLab. You can use this method if getting a linear trendline for a chart. The formula still works if you swap x 1 with x 2 and y 1 with y 2. The interest costs can be calculated randomly, but to use in the formula both costs should be different. I am given a value n and a value r0 and need to get a value from the given table. I don't know about other spreadsheets, but Microsoft just doesn't seem to want to put a linear interpolation function into Excel. 40%. Excel is an excellent tool for interpolation, as ultimately, it is a big visual calculator. Excel has an in-built function called INTERPOLATE that you can use to perform interpolation. Once we click OK, Excel automatically fills in the missing values by adding 3 to the each. In my career, about 90% of this work has involved batteries (always nonlinear) or sensors (frequently nonlinear). Select the row of x-values in the data table and name those “xvalues”. Its syntax is: FORECAST (NewX, known_y_pair, known_x_pair). Solved Examples. x = Known value. Follow these steps to learn how to do it. In general, an interpolant need not be a good approximation, but there are well known and often reasonable conditions where it will. 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. The FORECAST formula in Excel has three critical parameters: x, known_y’s, and known_x’s. ”. Therefore, you cannot ask the interpolation of a single number - rather, you need multiple numbers to determine your line, and from there you can ask what value. Linear interpolation is the process of estimating an unknown value of a function between two known values. Steps: For interpolation, we have a below formula. For given points (x 0 , y 0) and (x 1, y 1) the value at y for a known x can be calculated by the following. Rem Linear Interpolation from a x and y ordered data, for a value: Rem TODO: make it work with unordered Data. Actually you have a 3-d table - x and y are independent variables, and the one you need to find is z. Working through the "Finding the Function from the Log-Log Plot" section of the wiki page, I found that calculating $$ k = frac{log_{10}(y_2 / y_1) }{ log_{10}(x_2. From there, you can find the estimated value at any point between them. In our example of paddy growth, the first set of values is (4,2). - That proportion is calculated by how close we are to the second rate. 386 4 3 3. vq = interp1 (x,v,xq) returns interpolated values of a 1-D function at specific query points using linear interpolation. INC function introduced in Excel 2010. LINEAR formula to the cell where you want to add the interpolated value. I would do linear interpolation between the closest pair on the. Enter the formula =Interpol2D (y, x) into your spreadsheet where you want the interpolation result displayed. INTERPXY automatically. Step 1. Hi there, I'm in search for a formula that can perform linear interpolation between within arange of values. x is the point to perform the interpolation. Hello, I have a question about interpolation. Sheet1. Rem Linear Interpolation from a x and y ordered data, for a value: Rem TODO: make it work with unordered Data. There are various ways to interpolate: spline, polynomial, linear and so on. The FORECAST. The table will be placed in sheet 3 of the Excel Spreadsheet. Read on to know the popular and easy data interpolation methods in Excel. To perform the Linear Interpolate calculations, we use the FORECAST Excel formula. In the next example, we will find the specific volume of steam at a given temperature of 100 C and a given pressure of 20 kPa. Curve-fitting interpolation using LINEST and SERIESSUM-----The formula for linear interpolation is: So, in our example, the desired saturated pressure d at 38 C is: A nonsaturated example. The second value is in cell "A20" and has the value "1". Public Function InterpolateXY (ByRef X As Range, ByRef Y As Range, ByRef XRange As Range, ByRef YRange As Range, ByRef ValueTable As Range) As Double. 1. Step 1: Set up Data Model for Cubic Spline Interpolation. The main factor about spline is that it combines. Linear Interpolation Formula is the process of finding a value between two points on a line or curve. ) the data can be assumed to be linear. Below is a close-up of an interpolated data point. Arius provides functions for the Exponential, Inverse Power, Linear, and Weibull curves. Volatile Dim hi As Long Dim lo As Long Count = XRates. So why did we get 183. These are fill-in-the-blanks spreadsheet templates for performing the calibration curve fitting and concentration calculations for analytical methods using the calibration curve method. I use the following equations to find the two values either side of 50:Go into your code and set a break point (F9 key). I want to do this using formulae if possible. Excel has the =FORECAST. Here’s a description of what you need to know about each of these arguments: Argument. DrGenius. In simple terms, linear interpolation is a method of estimating a value between two known data points by assuming that the relationship between the two data points is linear or straight-line. Just read the context to get the basic insight about how to do interpolation, its formula, and. , C1), type the following formula: = (B5 - B3) / (A5 - A3) * (A4 - A3) + B3. Friday, March 1, 2013 at 8:04 pm. Replace "x" with the value you want to. Hi guys. 5 in cell B5 to indicate that we want to find the midpoint. Google groups is your friend. A linear interpolation function is also included. Method 1: Utilizing FORECAST. Linear Interpolation. 3 General Form of Newton’s Interpolating Polynomials The preceding analysis can be generalized to fit an nth-order polynomial to ( + 1) data points. Things to. LINEAR (x, known_y's, known_x's) to calculate the interpolated value. However my data is not linear for the entire data set. 3D (Surface) Interpolation Use INTERPXYZ to interpolate from a set of (x,y,z) data points. Hello, I'm not sure that I understand you correct what you mean with "non-linear interpolation". Now, we will show you how you can interpolate polynomially the value of Y from the given value of X by drawing a scatter chart in Excel. We would like to have max a x b jf(x) P n(x)j!0 as n. Then. Copy the code below into the module. 1. 1. The formula for linear interpolation is y = y 1 + ( x − x 1) ( y 2 − y 1) ( x 2 − x 1) Linear interpolation can also be used to find the median, 1 st quartile and 3 rd quartile. X1 and Y1 are "real" data points, so are X2 and Y2. A function to interpolate along Excel’s smooth line fit. 15(entered in cell I1) =FORECAST. Next, select the cell where you want the interpolated value to appear and use the formula =FORECAST. 2. Linear interpolation is a numerical method for curve fitting or estimating values between two known data points on a straight line. In our dataset, the values of the X coordinate and Y coordinate have a linear relation between them. It will be important later to distinguish. Formula implementation of interpolation. Click the Table > Design > Table Name > Enter T_Inputs > Press Enter. Data Formatted as a Table. To find the y and z values, we’ll just need to modify our formula to use the y-coordinates and z-coordinates of our points. Using the Lagrange Interpolation Formula, one may obtain the Lagrange polynomial. By mike0123m in forum Excel Formulas & Functions Replies: 8 Last Post: 09-28-2007, 02:09 PM. This is the ‘Linerp’ function. g. Utilizing FORECAST Function for Data Extrapolation in Excel. ) and some manually. t1 = 20, v(t1) = 517. This won't follow the nice curves along the XY plot, but it might still suit your purposes. linear interpolation of sparse data I have several lists of data, each sampled at different varying intervals. This looks very promising. When using Excel, there are two main ways to use linear interpolation. asked Nov 21, 2022 at 20:57. In Excel, we use a FORECAST function and a LOOKUP function to do a linear interpolation. I want to merge them into an average set of readings, but since they are each missing data and have readings at different times, I need to first fill-in all missing data using some (linear) interpolation. In more detail, the FORECAST function performs the actual interpolation using the linear interpolation equation shown above. , x and y) using repeated linear interpolation. To extrapolate data via way of means of the system, we want to apply factors of the linear chart: A(a, b) and B(c, d) The linear extrapolation system is: Y(x)=b+(x-a)*(d-b)/(c-a) You can input the system in step with factors of your data values and extrapolate the goal value. Linear interpolation would require me to put 5, 5+1. FORECAST() – This Forecast stand out functionThe FORECAST function in Stand out can be used to calculate or predict the long run value according to existing values and also the record. We’ll need to give the function a name – I’ll call it “LinInterp”. , (xn, yn) is defined as the concatenation of linear interpolants between each pair of data points. What I want is to rewrite the linear interpolation function so that it can calculate. Interpolation is a technique for approximating the value of a function between 2 well-known values. Re: TRILINTERP - linear interpolation of the 3D function. A function is required to perform interpolation (finding intermediate values). To use linear interpolation in Excel, you will need to determine the two known values, then use the slope-intercept form of the equation of a line to calculate the value that lies between them. Select the column of y-values in the same table and name those “yvalues”. INTERPXY is a versatile 2D interpolation function based on splines. 0. 3 is the value just before 3. Excel's solver tool is a really powerful way to perform nonlinear interpolation. ET MR Function Dictionary. Rows. Interpolation is a common way to approximate functions. =iferror(forecast. Interpolate in Excel Graph: 6 Ways. As we can see from the image above, point P is situated in the rectangle defined by the values 22. power head plot power head example Noise source plot S-parameter angles S-parameter example Noise source example Enter your data step-by-step plot closeupGenerating piecewise linear approximations for non-linear curves is a very common task. Linear interpolation, which is also called simply interpolation, thus is the ability to. To interpolate the missing value in cell B4 using linear interpolation: In an empty cell (e. FORECAST. Here, for this dataset, you can use the TREND function of Excel. A technique for two-dimensional interpolation on a rectangle is called bilinear interpolation. 96. Step 3: Utilize Excel VBA Code to Build a User-Defined Function. Excel - automatically fill down a row with date range matching a specific pattern. After that, go to Add Chart Element > Trendline > Linear. gives. Surprisingly, linear interpolation is quite hard to do in Excel. The following Microsoft Excel formula performs linear interpolation by calculating the interpolation step value: = (end-start)/ (ROW (end)-ROW (start)) where end is the cell address of the larger number, and start is the cell address of the smaller number. You also might try matrix formulas. Option Explicit Function Linterp2 (rX As Range, rY As Range, x As Double) As Double ' linear interpolator / extrapolator ' R is a two-column range containing known x, known y Dim lR As Long, l1 As Long, l2 As Long Dim nR As Long 'If x = 1. One of the basic approaches of data interpolation in Microsoft Excel is to apply the mathematical formula of linear interpolation. 47. I've been trying to work on a workbook function that will see the number that I'm looking at, find that number between two others, and then report back to me the vlookup value associated with that interpolation. , "eyeballed"). I have a very specific excel problem. x2 x 2 and y2 y 2 are the second coordinates. Logarithmic graphs often convert a non-linear equation into a linear one, making it suitable to interpolate unknown values. 3 and 56. Mathematical Equation for Linear Interpolation. target is the desired x-value(s) to interpolate for (a single value or a one-dimensional array of cells (e. Count > 1 Then: LinInterpolation = "Can only interpolate one value" Exit Function: End If: Dim value As Double: value =. Create a chart with your information. Given two known values (x1, y1) and (x2, y2), we can estimate the y-value for some point x by using the following formula: y = y1 + (x-x1) (y2-y1)/ (x2-x1) This tutorial explains howFirst use MATCH () to find the pair of values around the given value. what value should be returned if the X value interpolated against is outside the range of known X values, (argument cutOffAction, 0 = extrapolate; 1 = cut off. There are many ways to perform linear interpolation (or extrapolation) in Excel. .