The function is working ok, but i have to adjust the selection manually. With the VBA editor open, insert a module into the workbook by right-clicking on the workbook in the project window and selecting Insert>Module. interpolate ( method ='linear', axis =0, limit =None, inplace =False, limit_direction =None, limit_area =None, downcast =None, **kwargs)Interpolation between two values over a range. 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. The following Microsoft Excel formula performs linear. Now let's get into the math behind them. To perform linear regression in Excel, you'll need to use the "LINEST" function, which calculates the slope and intercept of the line that best fits the data. This is the linear interpolation function: Y=Y1+ (X-X1)x (Y2-Y1)/ (X2-X1)Pairwise linear interpolation using FORECAST Curve-fitting interpolation using LINEST and SERIESSUM These are demonstrated in the following image (click to open in a new window for a more-readable view). Read on to know the popular and easy data interpolation methods in Excel. Linear interpolation on a data set (red points) consists of pieces of linear interpolants (blue lines). The table will be placed in sheet 3 of the Excel Spreadsheet. ) the data can be assumed to be linear. I am using FORECAST function in Excel to estimate values using linear interpolation. You can monitor the calculated values in the Visual Basic Immediate window. Select the row of x-values in the data table and name those “xvalues”. In other words, interpolate the column E values corresponding to the column F values. xla, delete it, save the new file and seek. com Excel is an excellent tool for interpolation, as ultimately, it is a big visual calculator. Linear interpolation on a set of data points (x0, y0), (x1, y1),. Count Then Interpolate = _ "Ranges need to be the same size" Exit Function End If For hi = 1. 2. 3 and 56. 26 2M 0. Here Si(x) is the cubic polynomial that will be used on the subinterval [xi, xi+1]. Re: TRILINTERP - linear interpolation of the 3D function. So, the Excel formula equivalent to the above formula is, =(C3*(B6-E3)+C6*(E3-B3))/(B6-B3) and the formula evaluates to 40. 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. Use Mathematical Formula to Calculate Logarithmic Interpolation in Excel. Fill in a series that fits a simple trend, use functions to extend complex and nonlinear data, or perform regression analysis with the Analysis ToolPak Add-in. If our data set follows a linear pattern, we can use this method to. as in following example. Calculate, or predict, a future value by using existing values. Linear Interpolation - Key takeaways. My data consists of a number of latitude and longtitude points and I want to interpolate data every 50 feet between my 2 ponts and get the latitude and longitude of those points. Type. etc. actually a combination of linear interpolation and lookup/linear search. 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. you need to late bind the formula and use Application. In plain English, this Excel template draws a straight line between each point in a data set. Next, we will fit the quadratic regression model. I can have 10 x and y values, or 100. Step 3: Utilize Excel VBA Code to Build a User-Defined Function. The X and Y data are in columns A and B. So the formula for linear interpolation is y = y1 + (x-x1) (y2-y1)/ (x2-x1). If we plot this data, it might look like this: Linear Interpolation in. If you think your data is linear, and you want to try the approach identified by @tom10, try. 4 when we asked for the 80 th percentile earlier?FORECAST. Linear interpolation in Excel means forecasting or guessing the next value of any certain variable given on the current data. Vector x contains the sample points, and v contains the corresponding values, v ( x ). LAMBDA - Linear interpolation (L_InterpolateX) Interpolates within a table, on one dimension X or Y. TREASURY BOND YIELD CURVE by Andrew Chan Excel offers. 3 is the value just before 3. The cubic spline function smoothly interpolates between given data points. To do this, right-click on any data point and select ‘Add Trendline. From there, you can find the estimated value at any point between them. The following Microsoft Excel formula performs linear interpolation by calculating the interpolation step value: =(end-start)/(ROW(end)-ROW(start)) where end. Once you click on Data Analysis, a new window will pop up. 40%. forecast uses simple linear regression to predict a new y value based on known y and known x values. The TREND function returns values along a linear trend. First, organize your data into two columns with known values. Please keep in mind that interpolation is a statistical and mathematical tool that is used to predict the. 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. Function for linear interpolation and extrapolation with double entrance in first row and first column. 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. It is an nth-degree polynomial expression of the function f(x). Here, we create a. FORECAST. To interpolate the missing value in cell B4 using linear interpolation: In an empty cell (e. For example, i have 5, , ,10. xla (with new functions) In this page you can download an Excel Add-in useful to linear, quadratic and cubical interpolation and extrapolation. TREND returns the y-values along that line for the array of new_x's that you specify. 1. The values are not equidistant from each other. Step 1. Next, double-click on the trend line. . 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. The latest version of SRS1 Cubic Spline for Excel. - That proportion is calculated by how close we are to the second rate. A regular linear regression is calculated (with your data) as: =LINEST(B2:B21,A2:A21) which returns a single value, the linear slope (m) according to the formula: which for your data: is: Undocumented trick Number 1. 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". Copy the code below into the module. 5 then y=12. 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. As the name implies it fits a straight line to each. It keeps your code clean, short, tidy and. Excel replace value in a column using a pattern. The cubic spline interpolation is a piecewise continuous curve, passing through each of the values in the table. It has arguments SearchValue, SearchRange. But with some rectification, which I found in the web, it work fine. Nov 21, 2022 at 21:06. Given two known values (x1,. This equation will help you for interpolation. To find the required y, type the equation above in an Excel cell. Its syntax is: FORECAST (NewX, known_y_pair, known_x_pair). . use FORECAST () to get a linear interpolation between 19 and 22. Interpolated Yield Curve - I Curve: A yield curve derived by using on-the-run treasuries. [Edit]: You will need to sort your arrays on the x axis as @ImportanceOfBeingErnest adds. The formula works by: using the MATCH function to find the row in the inputs range just before the value being searched for (e. Image: Bilinear interpolation – axes and map representation. 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. We will show you 2 ways. 2) Calculate slope and intercept for each pair of points (for each firm) as part of the lookup table. The formula in B17 is:2 – Convert your Data into a Table. If you want actual and interpolated data all together in one array, then you will have to program the formula. 9. In this formula, (x1, y1) is referring to the first coordinate of the interpolation process. S. In our dataset, the values of the X coordinate and Y coordinate have a linear relation between them. 5 in this case. Simple linear regression equation: y = bx + a. This formula can also be understood as a weighted average. 3 General Form of Newton’s Interpolating Polynomials The preceding analysis can be generalized to fit an nth-order polynomial to ( + 1) data points. If your dates are formatted appropriately, Excel just reads them as numbers, so this will work fine. Because, as per the input data, the values corresponding to x = 1 is 1. 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. 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. If the target date is chronologically before the end of the. Two approaches come to mind: Pairwise linear interpolation using FORECAST. Linear Interpolation - Key takeaways. Lec. The TREND Function is an Excel Statistical function that estimates an unknown value based on linear regression. 3 is 5. Excel has an in-built function called INTERPOLATE that you can use to perform interpolation. 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). When using Excel, there are two main ways to use linear interpolation. known_y’s: An array of the dependent variable or range of data. #2. Interpolated values in between represented by color. 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. These values need to be in increasing order. Linear interpolation is used to find an unknown value of a function between any two known points. The interpolation problem is: given a set of pairs of values (x_i, y_i) for i in (0,N+1), find a function p(x) within a particular class (usually polynomials) such that p(x_i) = y_i. e. 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). 6. I have a table with many discrete sequential values down the rows of column 1, with corresponding values along each row down column 2. And our initial data set would look like this: Firstly, we can simply input the basic mathematical formula of linear interpolation in Excel to get the result. ____How to use:____ This Add-on does not have special UI on the sidebar. 1. 1) a LINEST () function to determine slope and intercept for each pair of points. The examples below assume that you know at least two points (x 1,y 1) and (x 2,y 2) and want to solve for y given x based on the equation for a line: y=mx+b, where m is the slope and b is the y-intercept. 24If you just want to interpolate using those two points, you just need to use the basic linear interpolation formula. 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. This uses Excel Forecast function =FORECAST (x,known_y's,known_x's). We have an experiment which have the variables x and y. You also might try matrix formulas. For linear interpolation have the sheet active and run the following. I do a lot of spreadsheets that requires linear interpolation using arrays. Excel charts are a convenient way to fit a curve to experimental data. 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. 1. I would like to write an Excel function that linearly interpolates between data points. The data is set up as follows. Step 1: Add the FORECAST. If we had instead. The array must be in ascending order. For interpolation, we have a below formula. However, Excel does not provide an interpolation feature. LINEAR () (2016) Statistical: Returns a future value based on existing values. reference for the tabulated x and y values and NewX with the x-value to interpolate, OR. You will use the FORECAST function when you need a function to forecast your data without making charts and graphs. 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. Methods. 1. Introduces a method to calculate interpolation step value in Excel. Solution: The procedure you use to solve this problem is essentially an extension of the method used for the single control parameter table. X1 and Y1 are "real" data points, so are X2 and Y2. To find the interpolated value for a particular x, Mathcad finds the two points between which the value falls and returns the corresponding y alue on the straight line between the two points . Each method is quite easy. Remember that likely none of us on this side of the internet has done this sort of calculation. Rows. The syntax of the INTERPOLATE function is: =INTERPOLATE (x, known_x’s, known_y’s) Where: x – the value for which you want to calculate the interpolated value. . You just need to insert the. As a result, when we apply this algorithm to the provided dataset, we receive the following interpolated y value: Interpolated value. A few methods of Interpolation are the following: Linear Interpolation: A straightforward approach for predicting the value of a function at a position between two known data points by determining the equation of the line that connects these two points. The functions of this Add-in are very simple to use and they have context help, through a chm file. 1. In other words, interpolate the column E values corresponding to the column F values. Using the Trendline, Excel can fit exponential, logarithmi. ”. 5%, PVL is $966. Log-linear would be wrong; forward points are commonly negative, and are merely a delta on the Spot. In this method, we will use a mathematical formula to calculate logarithmic interpolation in Excel. 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. Now, whenever the k value you specify is not a multiple of 1/(n-1), PERCENTILE. Rows. known_x’s: The independent array or range of data known to us. Converting Data to a Table. So if I understand you correctly you just want to interpolate in 3D. In more detail, the FORECAST function performs the actual interpolation using the linear interpolation equation shown above. Simple Implementation in ExcelIt will make possible a kind of interoperability among LibreOffice Calc, Google Sheet in interpolation matter. Origin provides four options for data interpolation: Linear, Cubic spline, Cubic B-spline, Akima Spline . Next, x refers to the known value, while y is the unknown value. Then, insert two columns named LogX and LogY. The formulas are: A3: =MATCH (A2,A6:A18) Performing linear interpolation in Excel is quick and straightforward. 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. Utilize Fill Command to Interpolate Time Series in Excel. 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). 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 (). 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. See the yellow-highlighted cells in my "corrected" sheet in the attached Excel file. Hello, I have a question about interpolation. 78. By mike0123m in forum Excel Formulas & Functions Replies: 8 Last Post: 09-28-2007, 02:09 PM. Disappointing. are the second coordinates x is the point to perform the interpolation y is the interpolated value. Examples of usage are included with the XonGrid archive. Introduces a method to calculate interpolation step value in Excel. If we consider two columns of data, for example: A B 100 97 110 120 135 135 157 166 What function or nested functions will return an "A" value if I input a "B" value of 147 ?-. 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. 96. Next, type in the formula =A2^2 in cell B2. x: It is the predicted value. 3) A lookup function (usually using approximate match option) to return slope and intercept at the specified date from the monthly table. known_x’s – a range of x. Tabular Data Extrapolate in. Here, the constant is usually set as 1 to derive the adjacent values. Step 2: Fill the formula with the desired values. Using Excel GROWTH Function for Nonlinear Interpolation. Linear interpolation would require me to put 5, 5+1. Linear Interpolation in Excel: Step-by-Step Example. Do Interpolation of Non-Linear 2D Data in Excel. Know the formula for the linear interpolation process. Example of bilinear interpolation on the unit square with the z values 0, 1, 1 and 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. e. An online linear interpolation calculator helps to find the interpolated values for the data points on a line or a curve. Then. Step 3: Finally, the interpolated point will be. Next, select the cell where you want the interpolated value to appear and use the formula =FORECAST. 31 6M 0. I have a very specific excel problem. This tutorial explains how to use linear interpolation to find some unknown. See the Excel file for details. It is a basic form of interpolation that assumes a linear relationship between the given data points. 6. The correct formula to use is of the form: =IFERROR. Rows. In reply to Day William's post on August 3, 2022. Hi guys. I assume that you want linear interpolation between 2 x values. If your data are linear when plotted as y vs log (x), then the data has a logarithmic relationship, as you pointed out. The latest version of SRS1 Cubic Spline for Excel. Compulsory Parameters: x: A numeric x-value for which you want to forecast a new y-value. =TREND (<known y's>,<known x's>,<new x's>) Which will return an array of new y's for each new x provided. known_x’s – a range of x-coordinates. You’ll get the desired result. Now let's do the linear interpolation. This is addressed in the topic Trendline Coefficients and Regression Analysis. This is the lower value for interpolation. For instance, Bresenham's algorithm interpolates points incrementally between the two endpoints of a line (Bresenham, J. See full list on engineerexcel. Steps: For interpolation, we have a below formula. #6. Since python is utilised, it is good practice to reuse existing functions already written by the community. Define a matching set of x values. It is easy to perform interpolation of non-linear 2D data in Excel. 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. I'm currently in college as a Civil Engineer. 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. The following Microsoft Excel formula performs linear interpolation by calculating the interpolation step value: = (end-start)/ (ROW (end)-ROW (start)) is the cell address of the larger number, and is the cell address of the smaller number. value = Application. Renaming an Excel Table Name. "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. (Linear behavior goes bananas when given non-linear inputs!) Returning the extents of the y_list for Interpolate[x] outside of x_list also means you know the range of your output value. As for Vlookup method, it just finds the closest month data. So the formula is y = y1 + (x-x1) (y2-y1)/x2-x1 . 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. Linear-Interpolation Method. , X1 & Y1. 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. Next, select all the air velocity numbers (cells D7-L15) and name them “zvalues”. Count If nR < 2 Then Exit Function If x < rX (1) Then ' x < xmin, extrapolate l1. There are many ways to perform linear interpolation (or extrapolation) in Excel. Here, we create a straight line that connects two values and estimates the future value. Now, for an unknown point of U(x,y), you want to know the y value for the known value of x. Interpolation requires a model. This would be by interpolation in the following part of your table. Use this value in the INDEX function to return the values of jc0, y0, and^i, as shown in the. Interpolation is a technique for adding new data points within a range of a set of known data points. If our data set follows a linear pattern, we can use this method to. Cubic Spline Method: This method fits a distinct cubic. . Here, for this dataset, you can use the TREND function of Excel. 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. Linear Interpolation formula is a method that constructs the new data points from the given set of data points. If you have some idea of the shapes of the underlying yield curves, you can work. Linear interpolation is used for fitting curves using linear polynomials. In this method, we will use a mathematical formula to calculate logarithmic interpolation in Excel. Next, select all the air velocity numbers (cells D7-L15) and name them “zvalues”. The formula need to be entered in the yellow cells (row 7), and should return the interpolated sieve diameter value for the percentages stipulated in row 6 For example; the value in. Function LinInterpolation(DataX As Range, DataY As Range, point As Range) As Variant: If point. Volatile Dim hi As Long Dim lo As Long Count = XRates. 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. Linear forecast formulas. What is the Interpolation Formula? The interpolation or linear interpolation formula finds the. Once we click OK, Excel automatically fills in the missing values by adding 3 to the each. 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. If you don’t see this option, then you need to first install the free Analysis ToolPak. 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 LinInterpolation(DataX As Range, DataY As Range, point As Range) As Variant: If point. I wrote a function in VBA to interpolate, giving the option of Arithmetic or geometric interpolation (but assuming arithmetic as the default), and using the standard vlookup function. ETS function syntax has the following arguments: Target_date Required. The cubic spline function smoothly interpolates between given data points. 4. Interpolation to a power function. Trilinear interpolation is a method of multivariate interpolation on a 3-dimensional regular grid. You want to obtain the value (by linear interpolation) for height of 7 and distance of 20. There's a linear interpolation (by computing fractions), but my recent try on logarithmic interpolation sometimes produces worse results than the linear one. Piecewise linear interpolation Figure 3. With just one cycle of historical data, Excel cannot identify a. 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). Select Regression and click OK. To start, place at least two columns of data in an empty Excel worksheet. 399. The data point for which you want to predict a value. In the interpolation formula, Y is the desired value or the output of a team with 13 members. You can also use Excel to calculate a regression with a formula that uses an exponent for x different from 1, e. Solution. A function to linearly. Consider now the problem of using an interpolation polynomial to approximate a given function f(x) on a given interval [a;b]. I would like to write an Excel function g such that for any x in [x_1, x_N]: g(x) = f(x), if x = x_iThen, click on the graph. A logarithmic scale simply means that valuesExcel's new LAMBDA functionality (Office 365/Excel 2021, beta version, insiders only) - the capability to define your own function within Excel directly - makes that several User Defined Function. Scene 7: Edit the formula and change the interpolation algorithm to three or linear interpolation then click OK. known_ys:. ”. Interpolation is a common way to approximate functions. I got three columns of interest: One with a timestamp in milliseconds and two with data. 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. What does this add-in do? It provides you with 2 new custom Excel functions: 1. เบราว์เซอร์นี้ไม่ได้รับการสนับสนุนอีกต่อไปIn the Insert menu, click on the Scatter icon and click on the scatter chart option with smooth lines and markers. forecast in your code. I don't know about other spreadsheets, but Microsoft just doesn't seem to want to put a linear interpolation function into Excel. value Excel Linear #Interpolation using the #FORECAST built-in function#excel #linearinterpolation #math #finance #accounting #science #engineering When you are doing a linear interpolation, you are approximating the function between points as a line. For Trend method, it is not working as the raw data, like L parameters is not linear data, if I use Trend method, for the several top month, return data will far from existing data. The future value is a y-value for a given x-value. The interpolation formula uses interpolation, which is the process involving finding a value between two points on the curve of a function. You only need to revise the input unknown X and input know. 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. The two points are t0 = 15 and t1 = 20. Linear Interpolation Formula is the process of finding a value between two points on a line or curve. The second value is in cell "A20" and has the value "1". – Scott Craner. Thank you in advance. Originally Posted by shg. 1. Define a vector of x values for which you want to interpolate the curve. In order to acomplish this I need to find two values in B, the closest to 50 without going over and the closest without going under e. The FORECAST. 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. Line 5 gives us the higher value for interpolation: 5: MINIFS(B:B,B:B,">" &VLOOKUP(D5, A:B, 2, TRUE)) It searches. Because on-the-run treasuries are limited to specific maturities, the yield of maturities that lies. Count <> YRates. FORECAST. This looks strange to me. Its general formula is. You can create a linear interpolation formula using Excel's MATCH and INDEX functions. When we click OK, Excel consequently fills in the. 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. In mathematics, bilinear interpolation is a method for interpolating functions of two variables (e. On a log-log plot, the same formula can be used by simply replacing all y and x values with their logarithms. It gives the y-intercept value where the linear regression line intersects the y-axis. 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. The formula is y = y1 + ( (x - x1) / (x2 - x1)) * (y2 - y1), where x is the known value, y is the unknown value, x1 and y1 are the coordinates that are below the known x value, and x2 and y2 are the coordinates that are above the x value. The median must be within the second group as 20 % are less and 20 % are more. With the VBA editor open, insert a module into the workbook by right-clicking on the workbook in the project window and selecting Insert>Module. Use the Add-in. 1 Answer.