Fig 1: Interpolation example - sample NA vector in column C (top panel), and interpolated value, with A1 style in FormulaBar and R1C1 returned by the Excel. So if you have 2-d table, you can find out which formula fits best your data, using Excel's "trend line" feature. So why did we get 183. e. Under the “Design” tab, go to “Add Chart Element. The mathematical equation for this case is as follows: y= y 1 + (x-x 1 )⨯ (y 2 -y 1 )/ (x 2 -x 1) We need the value of y corresponding to x, which makes point B (x,y). linear interpolation of sparse data I have several lists of data, each sampled at different varying intervals. Linear Interpolation formula is a method that constructs the new data points from the given set of data points. 1. Next, select all the air velocity numbers (cells D7-L15) and name them “zvalues”. A good solution from the file exchange can be interparc. x and y can be measured into pair ( x i, y i). It is considered to be the simplest of all methods to interpolate between two values when values are approximately linear. TREND returns the y-values along that line for the array of. x y 1 10 2 15 3 20. 1. Originally Posted by shg. The formula we use is: =C4+ (C5-C4)* (E4-B4)/ (B5-B4) Which translates to: Take the first rate, and add a proportion of the difference of the first rate and the second rate. Re: 3 Variable Table Lookup with linear Interpolation. Enter the data. That. For example, A3=3 and B3=7. Actually you have a 3-d table - x and y are independent variables, and the one you need to find is z. Code: Function interpsigma (lowsigma As Double, lowsigma2 As Double, highsigma As Double, highsigma2 As Double, lowvol As Double, lowvol2 As Double, highvol As Double, highvol2 As Double, sigmas As Range, vols As Range, targetsigma As Double) If targetsigma = lowsigma Then interpsigma = lowvol. You can use this method if getting a linear trendline for a chart. Rem Linear Interpolation from a x and y ordered data, for a value: Rem TODO: make it work with unordered Data. The N-1 Basis method is used by Excel’s legacy QUARTILE function and by the QUARTILE. #10. y =Unknown value. This is addressed in the topic Trendline Coefficients and Regression Analysis. 31 6M 0. In particular, take interpolation nodes a x 0 < x 1 < < x n 1 < x n b and produce the interpolation polynomial P n(x) that interpolates f(x) at the given node points. This will work on Excel 2007, but =FORECAST. Now I want to fill up the empty cells by linear interpolation. Based on an input value elsewhere, I want the formula to locate the two bounding values in column 1 and then to linearly interpolate the input value between the two (column 1, column 2) data points. I want to linearly interpolate between multiple points. The piecewise linear interpolant L(x) is a continuous function of x, but its first derivative, L′(x), is not continuous. Interpolate Excel Formula. 75%. Map a set of scattered (x,y) data points onto a uniform grid for curve plotting. which would have target achievement values from 101% to X%, and corresponding bonus award amounts ending. This results in a continuous curve, with a discontinuous derivative (in. Step 2: Click the Kutools > Insert Tools > Fill Blank Cells… . There are various ways to interpolate: spline, polynomial, linear and so on. My input data is as follows. =B2+ (A4-A2)* (B3-B2)/ (A3-A2) In the above example, the formula’s last section, highlighted in red, calculates how much time taken changes whenever the speed. The first step to performing linear interpolation with this method is to create a chart with all of your data to optimize your organization and ensure accuracy in your calculation. Method is the interpolation method (1 = Forward Flat, 2 = Backward Flat, 3 = Linear, 4 = Cubic. Whether you're new to Microsoft Excel or simply looking to pick up a few new tips and tricks, you're sure to enjoy this free software tutorial. Then. It is easy to perform interpolation of non-linear 2D data in Excel. e. Trilinear interpolation is a method of multivariate interpolation on a 3-dimensional regular grid. c. We called out the WorksheetFunction Index and Match. which is halfway through the median interval, as it should be: I deliberately made the example really simple (and symmetric). 6. This will work on Excel 2007, but =FORECAST. Formula of Linear Interpolation. etc. To convert five-point ratings to seven, you need to (1) adjust the scale to start at 0, (2) stretch the scale, and (3) adjust the scale again to start at 1. Excel has a standard worksheet function, forecast, which you can use for interpolation. 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. LINEAR calculates future value predictions using linear regression, and can be used to predict numeric values like sales, inventory, test scores, expenses, measurements, etc. As we can see from the image above, point P is situated in the rectangle defined by the values 22. I've constructed your case below, with data I've manually digitized (i. Our dataset basically consists of non-linear relations between Y and X Coordinates. See the Excel file for details. 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. Below is a close-up of an interpolated data point. 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). Check out the comprehensive interpolation documentation for more detail. 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. This pattern can be described inis the y-component (i. I was given a sheet that shows what it should look like when finished, but I just don't know how to get those values: It looks like the 2018 value should be 370,779, the 2019 value should be 458,258, and the 2020 value should be 566,375 (fod D5, E5, F5) - Your help is so appreciated by the way! I'm struggling on this one!You can choose multiple other non-linear interpolations too (quadratic, cubic and so on). Use INTERPXY to interpolate from a set of (x,y) data points at an arbitrary point. The formulas are: A3: =MATCH (A2,A6:A18) Performing linear interpolation in Excel is quick and straightforward. The syntax for the FORECAST. Method-3: Using the Combination of the IF, ISNA, VLOOKUP, AVERAGE, INDEX, and MATCH Functions. The formula for bilinear interpolation is: This is a complicated formula, but it can be broken down. Count If XRates. Function Definition: The code defines a function called TrilinearInterpolation that takes two input arguments (inputX and inputY) of type Double and returns a Double value as the result of the trilinear interpolation. Step 4: Determine Interpolate Y Value Using User-Defined Function in Excel. Steps: Accessibility center. INC function introduced in Excel 2010. So E8 will lie between 3 and 4, based on the. This tutorial explains how to use linear interpolation to find some unknown. We will show you 2 ways. Log-linear would be wrong; forward points are commonly negative, and are merely a delta on the Spot. If the points in the data set change by a large amount, linear interpolation may not give a good estimate. x is the point to perform the interpolation. We can add another series to highlight the input data points. Option Explicit Public Sub LinearFit () Dim rx As Range, ry As Range Dim x () As Variant, y () As Variant Dim i As Integer, j As Integer, N As Integer, M As Integer M = 6 'Columns N = 44 'Rows Set rx = Range ("A2"). See full list on engineerexcel. A function to linearly interpolate and extrapolate. Think of this as “the long-term estimate” of the data. Introduction. Converting Data to a Table. However, F8=8, which is an intermediate value not contained in column B. The FORECAST formula in Excel has three critical parameters: x, known_y’s, and known_x’s. The following Microsoft Excel formula performs linear interpolation by calculating the interpolation step value:. The first value is in cell "A1" and has the value "0". Count If nR < 2 Then Exit Function If x < rX (1) Then ' x < xmin, extrapolate l1. As to engineer usage, I may turn to python when no excel build-in function available. Here. To perform the Linear Interpolate calculations, we use the FORECAST Excel formula. The formula in B2 and down is =2*LN (A2) + 1. Bilinear interpolation - VBA code to be put in a module. In the example below, we will. Get it Now. You can use interpolation to fill-in missing data, smooth existing data, make predictions, and more. Follow these steps to use linear interpolation to find the median, quartiles or percentiles: Step 1. Given (x1, y1) and (x2, y2), we can estimate the y-value for a given x-coordinate. Therefore, a high-degree interpolation may be a poor predictor of the function between points, although the accuracy at the data points will be "perfect. 2. From this we get the simple linear interpolation formula x = fx2 +(1¡f)x1 (lin) : (3) Logarithmic scale The situation is a little less straightforward if the axis is not on a linear scale but rather on a logarithmic scale. When we click OK, Excel consequently fills in the. Its syntax is: FORECAST (NewX, known_y_pair, known_x_pair). It is easy to perform interpolation of non-linear 2D data in Excel. We're gonna build on some of what we learned in the environment modeling lesson, so if you need to review, click on this link. 1. xlsx (9. - So, we've seen two ways to calculate in-betweens: linear interpolation and Bézier curves. Using the Point-Slope formula, where the slope is (y 2-y. Linear interpolation on a data set (red points) consists of pieces of linear interpolants (blue lines). 827 1 10 28. Next, type in the formula =A2^2 in cell B2. LINEAR($I$1,INDEX(F2:H2,MATCH($I$1,$F$1:$H$1,1)):INDEX(F2:H2,MATCH($I$1,$F$1:$H$1,1)+1),INDEX($F$1:$H$1,MATCH($I$1,$F$1:$H$1,1)):INDEX($F$1:$H$1,MATCH($I$1,$F$1:$H$1,1)+1))One of the basic approaches of data interpolation in Microsoft Excel is to apply the mathematical formula of linear interpolation. The following Microsoft Excel formula performs linear interpolation by calculating the interpolation step value: =(end-start)/(ROW(end)-ROW(start)) where end. Interpolate Excel Formula Linear Interpolation – This method is quick. Then the recipe gives. Step 1: Open Visual basic Editor. To make the above LinearInterpolation function available in excel like other functions, you need to carry out the following steps:. – pizzettix. If our data set follows a linear pattern, we can use this method to. The FORECAST worksheet function can be used to do an extrapolation of future data points based on a linear regression of existing data. Because on-the-run treasuries are limited to specific maturities, the yield of maturities that lies. Select the chart to see two new tabs in the ribbon, “Design” and “Format. Scene 8: Now copy the formula to the remaining cells in the column, let's see how they look. Interpolation to a power function. Piecewise linear interpolation Figure 3. Suppose you have a point W(a,b) and V(c,d). 2) Once you have located the row and column that correspond to your entered D1 and L1, then you can use the INDEX() function to extract the four data points that represent the "corners" of the interpolation region 3) With those four points extracted from the table, you can then apply the formula given by Wikipedia (click through to the article. Two approaches come to mind: Pairwise linear interpolation using FORECAST. Copy the code below into the module. Description. , however, when I select multiple values it overrides the values in between the top and bottom cell. So the formula for linear interpolation is y = y1 + (x-x1) (y2-y1)/ (x2-x1). I do a lot of spreadsheets that requires linear interpolation using arrays. Steps: First of all, let’s assume Depth of Flow = X and Discharge = Y. Virtually every software comes with a function to perform linear. You just need to insert the formula. Determining an unknown rate using linear interpolation Rn = ((R1*(T2-Tn))+(R2*(Tn-T1)))/(T2-T1) Rn = R1 + SLOPE*(Tn-T1) Both formulas should always give same calculation Please address comments on this spreadsheet to. Using bilinear interpolation, for any given point x p and y p, we can extract the equivalent point (value) P (also known as z p ). Formula implementation of interpolation. INTERPXY is a versatile 2D interpolation function based on splines. 27 3M 0. A NON-LINEAR INTERPOLATION FORMULA 469 Let {P denote the distinct, hyperbolic conjugacy classes of G: and for each hyperbolic element P, let Py be the primitive element for which P = P'y. Next, select all the air velocity numbers (cells D7-L15) and name them “zvalues”. This equation will help you for interpolation. I now want to interpolate the values in cells "A2" to "A19" in such a way that a linear straight line is created between the values "0" and "1". Method 1: Mathematical Equation for Linear Interpolation. How to Use the Interpolation Calculator? The procedure to use the interpolation calculator is as follows: Step 1: Enter the first and second coordinate, and the point to perform the interpolation in the respective input field. Linear interpolation is the process of estimating an unknown value of a function between two known values. 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. Function for linear interpolation and extrapolation with double entrance in first row and first column. Polynomial Interpolation in Excel: Step-by-Step Procedures. When the data is not linear, the first thing we have to do is to find out the function's behavior. There are a few different types of interpolation techniques. 48 4Y 0. In this first method, we will extrapolate 2. The more data points that are used in the interpolation, the higher the degree of the resulting polynomial, and therefore the greater oscillation it will exhibit between the data points. Select the column of y-values in the same table and name those “yvalues”. Given an X vector, this function interpolates a vector Y based on the input curve (XY Range). Using a Mathematical Equation . Method-6: Using VBA Code to Do VLOOKUP and Interpolate in Excel. Finally, you will enter the equation into an Excel cell and use it to calculate the unknown value. Hi. 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. Once we click OK, Excel automatically fills in the missing values by adding 3 to the each. xlsm (with macro). The above formula is the Linear Interpolation Formula. The main factor about spline is that it combines. Rows. ET MR Function Dictionary. In this formula, (x1, y1) is referring to the first coordinate of the interpolation process. Linear interpolation is used to find an unknown value of a function between any two known points. I want to interpolate two values in Excel. Because AC is linear, that is, a straight line, the slope of the line (AB) connecting R 1 and R n is the same as the slope of line AC. 64. The case is best illustrated in the attached sheet. An alternative is to use INDEX; but my INDEX formula is messy. Step 3: Use the Interpolate Function. The symbols N (P) and N (Py) will denote the norms of P and Py. The pandas provide similar function. . Mathematics is the native language of the natural world. Enter the formula =Interpol2D (y, x) into your spreadsheet where you want the interpolation result displayed. 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. The x1 value is the value in the table that is just below our desired x-value of 230, and the x2. For instance, Bresenham's algorithm interpolates points incrementally between the two endpoints of a line (Bresenham, J. I assume that you want linear interpolation between 2 x values. A linear interpolation function is also included. User case. Follow these steps to learn how to do it. Disappointing. Linear interpolation in Excel means forecasting or guessing the next value of any certain variable given on the current data. These values need to be in increasing order. You only need to revise the input unknown X and input know. With this information the function will perform linear interpolation to find the specified value, or extrapolate to find the Y value if the X value is outside the range of known X values. #6. Nov 21, 2022 at 21:06. > spreadsheets like Quattro Pro do). Linear Interpolation. Method-5: Using the Combination of INDIRECT, ADDRESS, and MATCH Functions. The two points are t0 = 15 and t1 = 20. FORECAST. I can easily do a linear interpolation between these points, but would like to find a way to interpolate between the points on the generated curve, as the linear interpolations create a stepped (non-smooth) appearance. Data Formatted as a Table. 6. , rows or columns)). Here are the steps you can take: 1. So the formula for linear interpolation is y = y1 + (x-x1) (y2-y1)/ (x2-x1). Bilinear interpolation - VBA code to be put in a module. Introduces a method to calculate interpolation step value in Excel. When we click OK, Excel consequently fills in the. We will show you 2 ways. 3D (Surface) Interpolation Use INTERPXYZ to interpolate from a set of (x,y,z) data points. The nth-order polynomial is 𝑛( )= 0+ 1( − 0)+⋯+ 𝑛( − 0)( − 1)…( − 𝑛−1) As was done previously with the linear and quadratic interpolations, datainterpolation avec Excel sans fonctions en utilisant des simples formules ; vous cherchez une méthode simple et rapide pour faire de l'interpolation, dans ce. Write down the numbers that you are going to put. Select the range of 12 data points for the X Function Argument field. What separates this UDF from the countless other linear interpolation UDFs is that this function does not require your. respectively (and these satisfy N (P) > 1). Using GROWTH Function to Perform Exponential Interpolation. In this case first of all, you need to find closest larger and closest lower x values: Lower x: =MAX (IF (B1:L1<B5,B1:L1)) Larger x: =MIN (IF (B1:L1>B5,B1:L1)) Now need to find corresponding y's with HLOOKUP. there were some other logic issues that I fixed. = yk +sδk. "Click on ‘Insert’ and expand the dropdown for ‘Scatter Chart’ and select the ‘Scatter’ thumbnail (first one) Now a scatter plot will appear, and we will draw the regression line. 34 1Y 0. For example, A3=3 and B3=7. g. Type. And (x2, y2) refers to the second point of the interpolation process. First, we will find the x1 and x2 values. , Algorithm for computer control of a digital plotter, IBM Systems Journal, Vol 4, No 1, (1965), pp 2530. Known_y's represent the array of y-values you already know. LINEAR must be changed to =FORECAST (depreciated soon). 0. The formula to calculate linear interpolation is: Linear Interpolation (y) = y1+(x−x1) (y2 −y1) (x2 −x1) y 1 + ( x − x 1) ( y 2 − y 1) ( x 2 − x 1) where, x1 x 1 and y1 y 1 are the first coordinates. How does Excel compute its smoothing algorithm for curved lines in the XY scatter plots?New_y’s = InterpolateFunction(known_y’s, known_x’s, new_x’s), where Function relates to the equation used to fit the two known data points provided. . Add input cells for height and span in J1 and J2 respectively. 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 . 3. If we plot this data, it might look like this: Linear Interpolation in Excel What Is Linear Interpolation in Excel? Interpolation is a method of finding a value from known values. So the formula is y = y1 + (x-x1) (y2-y1)/x2-x1 . So here, “4” is the day, and “2” is the growth inches of the paddy. It uses exponential regression to predict a value. 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. INTERPXY automatically. which is 20000 + 0. Table of Contents hide. y is the interpolated value. An online linear interpolation calculator helps to find the interpolated values for the data points on a line or a curve. Then this will give any required value of y at a known value of x. In this formula, we are having terms as:If we talk about linear interpolation in Excel, we first need to understand what this term is. Right click on your chart > Add trendline > Under Trendline options, select one by one and see which is the best fit > Go down and check Display Equation on Chart. It is a basic form of interpolation that assumes a linear relationship between the given data points. But with some rectification, which I found in the web, it work fine. asked Nov 21, 2022 at 20:57. As the name implies it fits a straight line to each. Cell B2: Find the most recent recorded weight. Windows. I am using FORECAST function in Excel to estimate values using linear interpolation. Google groups is your friend. In more detail, the FORECAST function performs the actual interpolation using the linear interpolation equation shown above. Interpolation can be calculated in a variety of ways. Once you click on Data Analysis, a new window will pop up. Hello, I am trying to get an excel formula that will do linear interpolation for me. The function is working ok, but i have to adjust the selection manually. Then right click on the data series and select “Add Trendline…”. if x=1. Linear Interpolation – This method is quick and easy to use, also known as Lerp. linear(a2,c2:d2,e2:f2),na()) The TREND function returns values along a linear trend. 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 you would. Even better, attach the Excel file that resulted in estimate-y of 1. This is the lower value for interpolation. 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. If we plot this data, it might look like this: Linear Interpolation in. 2. Introduction to the Excel Template. To use these functions for linear interpolation, in our example, type the following equation in a cell: =SLOPE(C2:C15,B2:B15)*F2+INTERCEPT(C2:C15,B2:B15). 3 General Form of Newton’s Interpolating Polynomials The preceding analysis can be generalized to fit an nth-order polynomial to ( + 1) data points. To do this, right-click on any data point and select ‘Add Trendline. . We can use the following basic syntax to perform linear interpolation. Writing user defined Interpolation function in Excel. Linear interpolation, which is also called simply interpolation, thus is the ability to. . An interpolation strategy enables you to estimate a function's value at any location inside a rectangle if its value is known at each of the rectangle's four corners. 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. One frequent problem is that the SOC vs V OC curve is frequently not a one-to-one function. With optional arguments, you can control the interpolating spline properties. g. Skip to main content. Copy the formula above into Excel and replace KnownX and KnownY with the cell. Excel has an in-built function called INTERPOLATE that you can use to perform interpolation. You want to obtain the value (by linear interpolation) for height of 7 and distance of 20. ’. ____How to use:____ This Add-on does not have special UI on the sidebar. Will be testing it out shortly and I'll leave feedback. 76 and at the higher discount rate rH of 9%, PVH is $934. I successfully expanded the X-values to 1000 rows by splitting the list at the MIN value. Jul 16, 2003. The functions are accessed just like any other standard Excel function. Use the equation displayed on the chart to interpolate values within. 78. 26 2M 0. 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). If you want actual and interpolated data all together in one array, then you will have to program the formula. The functions are accessed just like any other standard Excel function. The Fill Series feature under the Editing group on the Home tab is the quickest way to fill in the missing information. I will include the code below. 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. Let’s understand more about linear interpolation excel. 2) a lookup function to return the slope and intercept specific to the desired unkown. Here, we create a straight line that connects two values and estimates the future value. Utilizing TREND Function for Exponential Interpolation in Excel. The order the data is coming is variable and the difference of the timestamps is also variable. I have a column with values and empty cells. Here Si(x) is the cubic polynomial that will be used on the subinterval [xi, xi+1]. Since python is utilised, it is good practice to reuse existing functions already written by the community. In my career, about 90% of this work has involved batteries (always nonlinear) or sensors (frequently nonlinear). Linear Interpolation - Key takeaways. 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. 4. 1. Then go into the spreadsheet and get that cell to calculate. 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. Once we have our data set, we must create a chart based on those values. Linear Interpolation. Examples of usage are included with the XonGrid archive. As a result, when we apply this algorithm to the provided dataset, we receive the following interpolated y value: Interpolated value. Basically what I want is a LAMBDA function that could be called XINTERPOLATE or something like that that takes the Road and the Station as inputs. Copy the value in C1 and paste it in cell B4 to replace the missing value. The GROWTH function is a special function to interpolate non-linear data. linear(a2,c2:d2,e2:f2),na())which is the formula for linear interpolation in the interval (,). <colgroup><col width. Just read the context to get the basic insight about how to do interpolation, its formula, and. Thus, our formula would become “ =BicubicInterpolation (B13,B14 ”. Browser ini sudah tidak didukung. The calculator plots the interpolated point on a line and shows a step-by-step solution by using linear interpolation formula. By mike0123m in forum Excel Formulas & Functions Replies: 8 Last Post: 09-28-2007, 02:09 PM. Every time you change one of the referenced values the calculation will be run again. Download the Excel file for details. The second value is in cell "A20" and has the value "1". HTH, Bernie MS Excel MVP Function Interpolate(Xnow As Double, _ XRates As Range, YRates As Range) As Double Application. One relies on creating a curve of best fit taking into account the entire data set. INTERPXY is a versatile 2D interpolation function based on splines. 0. The TREND Function is an Excel Statistical function that estimates an unknown value based on linear regression. 6. Example: Linear Interpolation in Excel: Consider the following dataset in Excel: Linear Interpolation in Excel. Apr 22, 2021. The cubic spline function smoothly interpolates between given data points. It's often good to view Interpolation on a graph so that it becomes clearer what we're doing: - So. Furthermore, scroll down and check the option ‘ Display Equation on chart ’. 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 closeup Step 3: Use the Interpolate Function. Press Enter. In Excel,. =iferror(forecast. Example of bilinear interpolation on the unit square with the z values 0, 1, 1 and 0. Select Regression and click OK. Excel has the =FORECAST. 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. Bei der Interpolation wird ein unbekannter Wert einer Funktion zwischen zwei bekannten Werten geschätzt. Linear interpolation is often not accurate for non-linear data. Table of Contents. x. read more to determine the unknown value from the two known points. 000 3 2 2.