excel linear interpolation formula. Disappointing. excel linear interpolation formula

 
 Disappointingexcel linear interpolation formula  The existing values are known x-values and y-values, and the future value is predicted by using linear regression

And (x2, y2) refers to the second point of the interpolation process. LINEAR function predicts a value based on existing values along a linear trend. The formula for linear interpolation is: y = y 1 + (y 2 – y 1) * (x – x 1) / (x 2 – x 1) where: x is the known value, y is the unknown value, x 1, y 1 are coordinates below the known value, x 2, y 2 are coordinates above the known value. linear interpolation 2-way table. Two approaches come to mind: Pairwise linear interpolation using FORECAST. The calculation of IRR with linear interpolation would require a three-step approach. there were some other logic issues that I fixed. Let’s understand more about linear interpolation excel. The data to interpolate is in A1:B14. Count If nR < 2 Then Exit Function If x < rX (1) Then ' x < xmin, extrapolate l1. You could change the Forcast line to: Sheets (1). 96. x2 x 2 and y2 y 2 are the second coordinates. Video transcript. Re: Double interpolation. “X” is the first set of values, and “Y” is the second set of values. 78. 2. 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. The GROWTH function is a special function to interpolate non-linear data. 24 1M 0. Linear Interpolation – This method is quick and easy to use, also known as Lerp. y is the interpolated value. If you don’t see this option, then you need to first install the free Analysis ToolPak. This tutorial explains how to perform linear interpolation in Excel, including a step-by-step example. 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. This looks very promising. Closer would be log-linear on the outrights (Spot plus forward points), but even that is not worth bothering with. My input data is as follows. Method-5: Using the Combination of INDIRECT, ADDRESS, and MATCH Functions. The cubic spline function smoothly interpolates between given data points. It approximates the value of a function at an intermediate point within the local axial rectangular prism linearly, using function data on the lattice points. เบราว์เซอร์นี้ไม่ได้รับการสนับสนุนอีกต่อไปIn the Insert menu, click on the Scatter icon and click on the scatter chart option with smooth lines and markers. The following Microsoft Excel formula performs linear interpolation by calculating the interpolation. 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:. The order the data is coming is variable and the difference of the timestamps is also variable. Declaring. When we click OK, Excel consequently fills in the. Rows. I'm trying to construct a workbook with the ability to interpolate between 2 values. You can also implement a user defined function (UDF) interpolateX. Verma @ 1 person found this reply helpful. Given (x1, y1) and (x2, y2), we can estimate the y-value for a given x-coordinate. Here, we have two variables, i. So here, “4” is the day, and “2” is the growth inches of the paddy. Interpolation is a common way to approximate functions. Interpolation is the process of estimating an unknown. Function approximation: Linear interpolation can be used to approximate a function based on a set of. You can use Excel to project values that are based on existing data or to automatically generate values based on linear or growth trend calculations. Refer to the attached example image if needed. If there is a row containing data 1, then the cell with data 2 is empty and vice versa. Here, for this dataset, you can use the TREND function of Excel. LINEAR (x, known_y's, known_x's) to calculate the interpolated value. 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. For example, if you're using data about how sales increased as a company hired more sales professionals, the numbers of sales professionals go in column A, and the corresponding total sales go in column B. Interpolation can be calculated in a variety of ways. It is usually applied to functions sampled on a 2D. I would not worry about the volatile nature of the OFFSET formula if you do not have too many. Forecast (temp, Array (indexys, indexys1),. Its syntax is: FORECAST (NewX, known_y_pair, known_x_pair). Use Tab to toggle from the function arguments fields. I’ve looked at the thirty-three-and-a-third percentile expecting it to usually be a simple linear interpolation of the 33rd and 34th percentiles (ie. . 0. The Y- coordinates even start descending and ascending multiple times. Interpolation requires a model. There are various ways to interpolate: spline, polynomial, linear and so on. 219. =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. Excel charts are a convenient way to fit a curve to experimental data. Rows. Find the place within the data where the value you are looking to find is positioned, e. 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. See full list on engineerexcel. This the ‘Bezier’ function. Excel and OpenOffice Calc Versions. Click on the drop-down list of “Add Chart Element” >> “Trendline” >> “Linear. Beispiel: Lineare Interpolation in Excel. See the yellow-highlighted cells in my "corrected" sheet in the attached Excel file. 5 in cell B5 to indicate that we want to find the midpoint. Example of bilinear interpolation on the unit square with the z values 0, 1, 1 and 0. [Example. It is a polynomial expression of the function f at the nth degree (x). y = y1 + (x – x1) * (y2 – y1) / (x2 – x1) Where: x1 and x2 are the known values of the independent variable that represent the unknown value of x that needs a. forecast in your code. I took 2 screenshots. The following Microsoft Excel formula performs linear interpolation by calculating the interpolation step value:. Next, let’s create a scatter plot to check if the data follows a linear trend. Nonlinear Interpolation With Excel To Construct U. 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. 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. Table of Contents hide. 5 Then Stop nR = rX. Interpolation in MATLAB ® is divided into techniques for data. It gives the y-intercept value where the linear regression line intersects the y-axis. You just need to insert the formula. Select the range of 12 data points for the X Function Argument field. Get it Now. Once we have our data set, we must create a chart based on those values. y is the interpolated value. Using the Lagrange Interpolation Formula, one may obtain the Lagrange polynomial. Count If nR < 2 Then Exit Function If x < rX (1) Then ' x < xmin, extrapolate l1. Adding the module. Do Interpolation of Non-Linear 2D Data in Excel. . The end result i am looking for would look. This is the lower value for interpolation. 6. 4. From there, you can find the estimated value at any point between them. 5 then y=12. 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 . The data point for which you want to predict a value. F9 might work, or select the cell containing the function and hit F2 and enter. Lec. For linear interpolation, the model is the unique piecewise linear function that passes through each sample point and is linear on each interval [x i, x i+1]. 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. Next, select all the air velocity numbers (cells D7-L15) and name them “zvalues”. The piecewise linear interpolant L(x) is a continuous function of x, but its first derivative, L′(x), is not continuous. This will work on Excel 2007, but =FORECAST. You'll need much more advanced software for that, such as MatLab. Call the linterp function to perform linear interpolation between the data points. Interpolated Yield Curve - I Curve: A yield curve derived by using on-the-run treasuries. docx. But my guessing, base on your explanation, is that you need to use the FORCAST function, which in its general form not return the most precise result. In this case, copy-and-paste your formula from the Formula Bar. t0 = 15, v(t0) = 362. One relies on creating a curve of best fit taking into account the entire data set. Step 3: Utilize Excel VBA Code to Build a User-Defined Function. Finally, you will enter the equation into an Excel cell and use it to calculate the unknown value. Interpolation is the process of estimating an unknown value of a function between two known values. Linear interpolation would require me to put 5, 5+1. 40. 3 and 56. (x2,y2) = Second point of the interpolation process. If you are not committed to Excel, you could try Quattro Pro that does have a built in linear interpolation (@LINTERP()) function. This simple and powerful Excel linear interpolation function was developed using VBA and can be called from within your excel workbook. For example, Code: A --B-- 1 x y 2 1 1. Copy the code below into the module. We will show you 2 ways. 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. The table will be placed in sheet 3 of the Excel Spreadsheet. I have a very specific excel problem. vq = interp1 (x,v,xq) returns interpolated values of a 1-D function at specific query points using linear interpolation. To perform the Linear Interpolate calculations, we use the FORECAST Excel formula. I have a model where a certain boost leads to a certain rate. The entered value of the known_ys argument in cells “B3:B10”. 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. Next, we will select the range of our 4×4 grid of neighboring data points. Here’s a description of what you need to know about each of these arguments: Argument. Think of this as “the long-term estimate” of the data. 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. One frequent problem is that the SOC vs V OC curve is frequently not a one-to-one function. For interpolation, we have a below formula. 3 is the value just before 3. Method 3: Interpolate in. x - the independent variable you are using to predict y. If you have multiple sets of data that are sampled at the. Rows. The future value is a y-value for a given x-value. Examples of usage are included with the XonGrid archive. 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. Hello. Here Si(x) is the cubic polynomial that will be used on the subinterval [xi, xi+1]. 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. If you can express your problem as a system of linear equations, excel has a few matrix formulas. If the r0 value falls between two values a function needs to interpolate and. Then this will give any required value of y at a known value of x. There surely is an easy way, as the smoothed curves are so easily generated by the graphing function of Excel. Then. 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 (). 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. You have to use it as native function of Google Sheet 1. Use INTERPXY to map a scattered (x,y) data points onto a uniform grid for easy plotting in Excel. 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). x = Known value. Use Mathematical Formula to Calculate Logarithmic Interpolation in Excel. Step 2: Input Required Data into Cubic Spline Model. Interpolation is the process of estimating an unknown value of a function between two known values. Excel - automatically fill down a row with date range matching a specific pattern. . 32 9M 0. But for small portions of the table (for example between rows 1 and 2, 2 and 3, 3 and 4. Then the recipe gives. 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. Use the Add-in. The bilinear interpolation process uses the average of the data at each corner of. 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. g. 4. xll and for the 64 bits version of Excel select XonGrid-w64. Log-linear would be wrong; forward points are commonly negative, and are merely a delta on the Spot. Then go into the spreadsheet and get that cell to calculate. Comprehending Interpolation. Choose the Scatter chart type and select the scatterplot that best represents your data. 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. The formula for bilinear interpolation is: This is a complicated formula, but it can be broken down. Formula implementation of interpolation. Write down the numbers that you are going to put. Select the chart to see two new tabs in the ribbon, “Design” and “Format. Alternatively,. 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. Excel Linear #Interpolation using the #FORECAST built-in function#excel #linearinterpolation #math #finance #accounting #science #engineeringWhen you are doing a linear interpolation, you are approximating the function between points as a line. Please keep in mind that interpolation is a statistical and mathematical tool that is used to predict the. Cell A3 indicates which pair of points to interpolate between. What separates this UDF from the countless other linear interpolation UDFs is that this function does not require your. Linear interpolation on a set of data points (x0, y0), (x1, y1),. Interpolation is a method of estimating and constructing new data points from a discrete set of known data points. When the data is not linear, the first thing we have to do is to find out the function's behavior. The VBA code of this function is found at the. Solved Examples. 2,075. The FORECAST function, which can be used in Excel to perform linear interpolation, is =FORECAST. Formula implementation of interpolation. Check out the comprehensive interpolation documentation for more detail. LINEAR(X,knownY,knownX) function. gives. x and y can be measured into pair ( x i, y i). So, the Excel formula equivalent to the above formula is, =(C3*(B6-E3)+C6*(E3-B3))/(B6-B3) and the formula evaluates to 40. The following Microsoft Excel formula performs linear interpolation by calculating the interpolation step value: =(end-start)/(ROW(end)-ROW(start)) where end. 41 3Y 0. Value 'Get. The Fill Series feature under the Editing group on the Home tab is the quickest way to fill in the missing information. 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. Using Excel GROWTH Function for Nonlinear Interpolation. If you're stuck working in Excel. I offered the following suggestions. 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. See the yellow-highlighted cells in my "corrected" sheet in the attached Excel file. Let's start with the simpler version, linear interpolation. Excel Linear Interpolation Linear interpolation in excel means forecasting or guessing the upcoming next value of any certain variable given on the. Count If nR < 2 Then Exit Function If x < rX (1) Then ' x < xmin, extrapolate l1 = 1: l2 = 2: GoTo. asked Nov 21, 2022 at 20:57. + b n x n + a. This video looks at two problems in PTC Mathcad addressed w. The median must be within the second group as 20 % are less and 20 % are more. The interest costs can be calculated randomly, but to use in the formula both costs should be different. An online linear interpolation calculator helps to find the interpolated values for the data points on a line or a curve. HTH, Bernie MS Excel MVP Function Interpolate(Xnow As Double, _ XRates As Range, YRates As Range) As Double Application. To start, place at least two columns of data in an empty Excel worksheet. Use the equation displayed on the chart to interpolate values within. 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. To interpolate the missing value in cell B4 using linear interpolation: In an empty cell (e. Outside-range values are easily diagnosed because it throws errors in the intermediate table when you go off the edges. Function LinInterpolation(DataX As Range, DataY As Range, point As Range) As Variant: If point. 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. in Excel. I successfully expanded the X-values to 1000 rows by splitting the list at the MIN value. The formula works by: using the MATCH function to find the row in the inputs range just before the value being searched for (e. A linear interpolation function is also included. Here are the steps you can take: 1. Linear interpolation in Excel means forecasting or guessing the next value of any certain variable given on the current data. 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. Tabular Data Extrapolate in. 64. You should be brought into the editor with your code execution paused at the line where you set the breakpoint. y =Unknown value. This is the lower value for interpolation. x: It is the predicted value. Gary''s Student. The model is usually undefined outside of the range of the data, although there are various (nonunique) ways to extrapolate the model beyond the range. Select the range of 12 revenue goals for the Y Function Argument field. 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. Next, x refers to the known value, while y is the unknown value. Here, we create a straight line that connects two values and estimates the future value. Enter the data. A technique for two-dimensional interpolation on a rectangle is called bilinear interpolation. Formula of Linear Interpolation. LINEAR (B1,B3:B10. linear interpolation of sparse data I have several lists of data, each sampled at different varying intervals. 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. Google groups is your friend. The functions are accessed just like any other standard Excel function. We can use the following basic syntax to perform linear interpolation. In other words, interpolate the column E values corresponding to the column F values. com Excel is an excellent tool for interpolation, as ultimately, it is a big visual calculator. When using Excel, there are two main ways to use linear interpolation. 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. This formula can also be understood as a weighted average. Additionally, you can extrapolate a sheet or even a periodic template. The linear interpolation draws straight lines from each point to the next. ”. 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. Cell A2: Copy your weight data into the first column. If you select columns, please check the From top to bottom option. This tool, interpolation, is not only useful in statistics. Follow these steps to learn how to do it. This is the easiest way to interpolation by set up formula only 1 time and we can use this forever. Linear Interpolation. 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. Disappointing. Define a set of y values. I have Lat 1, Long 1 & Lat 2, Long 2 I need help writing a formula to do. The linear interpolation is commonly used in computer graphics. Step 2: Now click the button “Calculate” to get the result. Use INTERPXY to interpolate from a set of (x,y) data points at an arbitrary point. If you have some idea of the shapes of the underlying yield curves, you can work. Follow. 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. This pattern can be described inis the y-component (i. By mike0123m in forum Excel Formulas & Functions Replies: 8 Last Post: 09-28-2007, 02:09 PM. 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. To make the above LinearInterpolation function available in excel like other functions, you need to carry out the following steps:. In other words, interpolate the column E values corresponding to the column F values. known_x’s – a range of x-coordinates. We have an experiment which have the variables x and y. , x and y) using repeated linear interpolation. 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. Apr 22, 2021. Jun 12, 2013. which is halfway through the median interval, as it should be: I deliberately made the example really simple (and symmetric). What is the Interpolation Formula? The interpolation or linear interpolation formula finds the. The formula in B17 is:2 – Convert your Data into a Table. In the Format Trendline pane, select the options to Display. Methods. Mathematical Equation for Linear Interpolation. Function LinInterpolation(DataX As Range, DataY As Range, point As Range) As Variant: If point. You can monitor the calculated values in the Visual Basic Immediate window. 1. 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 . [SOLVED] 3d interpolation of a table. Method 2: Interpolate in Excel Graph Using Trendline. The formula for bilinear interpolation is: This is a complicated formula, but it can be broken down. I then use index match to get the corresponding values in column C to populate the linear interpolation formula. Let's say we have two data series x_i and y_i such that for all i in [[1,N]], y_i = f(x_i) where f is a non-linear function. Outside this interval, the formula is identical to linear extrapolation. Next, select the cell where you want the interpolated value to appear and use the formula =FORECAST. Cell B2: Find the most recent recorded weight. It works fine except when the formula gets to the end of the number its trying to interpolate with. A function to linearly interpolate and extrapolate. However, F8=8, which is an intermediate value not contained in column B. Example of Interpolation Formula (With Excel Template) Let’s take an example to understand. The resulting scatter chart will plot the result of our cubic spline interpolation. HOW TO ATTACH YOUR SAMPLE WORKBOOK: Unregistered, Fast answers need clear examples. S, S’, S” are all continuous function on [a, b]. Example: Linear Interpolation in Excel: Consider the following dataset in Excel: Linear Interpolation in Excel. The interpolation method is used to find the new data points within the range of a discrete set of known data points. "MrShorty" wrote: >. a polynomial that assumes certain values at each given position. Dados dos valores conocidos (x 1 , y 1 ) y (x 2 , y 2 ), podemos estimar el valor de y para algún punto x usando la siguiente fórmula: y = y 1 + (xx 1 ) (y 2 -y 1 ) / (x 2 -x 1. The case is best illustrated in the attached sheet. As a result, when we apply this algorithm to the provided dataset, we receive the following interpolated y value: Interpolated value. , see screenshot: Step 3: In Fill Blank Cells dialog box, check the Linear values option and From left to right option. This adjustment corrects calculations that yielded incorrect R 2 values and aligns the R 2 calculation with the LINEST function. If your data are linear when plotted as y vs log (x), then the data has a logarithmic relationship, as you pointed out. 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. Known_y's represent the array of y-values you already know. It finds the unknown values in the table. The expression that helps calculate extrapolation is as follows: Y (x) = Y (1)+ (x- x (1)/x (2)-x (1)) * (Y (2) – Y (1)) The formula for linear extrapolation can be divided into the following steps: First, one must analyze the data to. 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). 6. Utilizing TREND Function for Exponential Interpolation in Excel. We’ll need to give the function a name – I’ll call it “LinInterp”. LINEAR (B1, i. In this article, we will show you two. . 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. Create a chart with your information. You can use this method if getting a linear trendline for a. Simple Implementation in ExcelIt will make possible a kind of interoperability among LibreOffice Calc, Google Sheet in interpolation matter. After that, go to Add Chart Element > Trendline > Linear. , X1 & Y1. The Linear Interpolation Formula is a mathematical method used to estimate an unknown value within a range of known data points, assuming a linear relationship between them. We called out the WorksheetFunction Index and Match. Volatile Dim hi As Long Dim lo As Long Count = XRates. 1. To demonstrate the methods we will use the following dataset. Use the following Formula in the cell I2 to interpolate for the value 0. respectively (and these satisfy N (P) > 1). Rem Linear Interpolation from a x and y ordered data, for a value: Rem TODO: make it work with unordered Data. g. Using the Trendline, Excel can fit exponential, logarithmi. ’. 386 4 3 3. 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. 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). – pizzettix. This tip explains how to use the function. Step 2: Fill the formula with the desired values. Dr. LINEAR must be changed to =FORECAST (depreciated soon). In the interpolation formula, Y is the desired value or the output of a team with 13 members.