numpy. Undaunted, I wrote my own version of nancumsum and promptly shared it on the File Exchange. For the columns B to H I would like to find NaN values for each column, sum them, and in the end, store all these in a new table. Before that, the easiest approach was to use the Statistics toolbox nansum() mean() these days also has 'omitnan' flag, and in older versions the Stats tool was nanmean() 2 Comments. nanmean giving nansum output. Why I am getting sum =NaN. . Show -1 older comments Hide -1 older comments. y = nanmean (X,vecdim) returns the mean over the dimensions specified in the vector vecdim . It's just named "the sum function called with the 'omitnan' flag. Made for data-oriented projects in general; Open-source; Handles big data (very large datasets) Large number of ready-made packages; Built-in ways to professionally visualize data {"payload":{"allShortcutsEnabled":false,"fileTree":{"":{"items":[{"name":". Unbiased estimates are provided. For example, if X is a matrix, then nansum(X,[1 2]) is the sum of all non-NaN elements of X because every element of a matrix is contained in the array slice defined by dimensions 1 and 2. The function computes the means after removing NaN values. MATLAB Language Fundamentals Matrices and Arrays Creating and Concatenating Matrices. Bish Erbas on 27 Sep 2018. I can only get it work if all the values are nan and you are using mean. I am using movie dataset from Kaggle. % Enter your MATLAB Code below % Enter your MATLAB Code below % Read Output Water Quantity over the past month from a ThingSpeak channel and write % the average to another ThingSpeak channel. One work-around would be to temporarily convert the datetime to a numeric representation (for example, the number of seconds since some reference time). >> d = datetime (2015,1,1) + caldays (randi (2,5,1)); nanmin is not recommended. multiplying/dividing matrices that contain. The Matlab statistics toolbox has the functions nanmax, nanmean, nanmedian, nanmin, nanstd and nansum that do precisely that. array function and subsequently apply any numpy operation:. We have set it to float 64 bits to avoid overflow. For example, if X is a matrix, then nansum(X,[1 2]) is the sum of all non-NaN elements of X because every element of a matrix is contained in the array slice defined by dimensions 1 and 2. Example m = magic (3); m ( [1 6 8]) = [NaN NaN NaN] m = NaN 1 6 3. You do not need to change the input arguments. You can use nansum. If X is a vector, then nanmean(X) is the mean of all the non-NaN elements of X. Sorted by: 3. How do you exclude the NaN values in the last row in order to output an average of all the real number values?But removing nanmean, nansum, nanstd, etc from the basic Matlab was a serious mistake. x = linspace (0,10); y = sin (x); plot (x,y); Set the x -axis limits mode to manual so that the limits do not change. If dtype is not specified, it defaults to the dtype. I have data in excel that is 17 columns by 4800 rows. 044 0. Each element of the output array is the. For example, if X is a matrix, then nansum(X,[1 2]) is the sum of all non-NaN elements of X because every element of a matrix is contained in the array slice defined by dimensions 1 and 2. de 2016. nanmean arithmetic mean, ignoring NaNs;. The data is collected once every day. MATLAB: How to force nansum(NaN+ NaN) = NaN, not 0. 145 0. Steven Lord el 4 de Nov. For simplicity, lets pretend that only the second fraction of the equation is there. hi, I have created one mat file (attached). It is also used for representing missing values in a dataset. , you can use the 'nan' variant of those functions: nansum, nanmean, nanstd, nanmax, nanmedian. S = sum ( ___,outtype) returns the sum with the. See syntax, description, input and output arguments, and examples of nansum in MATLAB. The function computes the sums after removing NaN values. example. S = sum (A) returns the sum of the elements of A along the first array dimension whose size is greater than 1. The multivariate normal cumulative distribution function (cdf) evaluated at x is the probability that a random vector v, distributed as. the estimation of mean values and covariance matrices from incomplete datasets, and. nansum. Overview; vector3d. #. {"payload":{"allShortcutsEnabled":false,"fileTree":{"":{"items":[{"name":"calendar","path":"calendar","contentType":"directory"},{"name":"cm_and_cb_utilities","path. the help command (image below) is also referencing nansum's functionality. shp','UseGeoCoords',true); load IntMATLAB1. Learn more about matlab function MATLAB function 'nanmean' is behaving like nansum and I don't know why. Ogive optimization toolbox. Depending on your signal, using a linear interpolation can make sense. For matrices, nansum (X) is a row vector containing the sum of the non- NaN elements in each column of X. I am trying to calculate a cosine similarity using Python in order to find similar users basing on ratings they have given to movies. Returns the average of the array elements. 063 -0. Make sure that you use nansum or sum with the 'omitnan' option, because your calculation sometimes produces NaN values,. " It does not say that this depends on the presence or absence of real numbers. Show 2 older comments Hide 2 older comments. Learn more about nansum, function, monthly_sum MATLAB I use the function below to perform the monthly precipitation accumulator, however, when there are days without NaN measurements in a given month, the result for that month is zero. If X is a multidimensional array, then nanmean operates along the first nonsingleton dimension of X. Also, using nansum() is not recommended as you can see from its documentation page. mat. For vectors x, nanmedian(x) is the median of the remaining elements, once NaN values are removed. NANSUM is OBSOLETE; use SUMSKIPNAN instead. So far I have done this for column B: Theme. If installing the toolboxes offline, the installation files must match the update version of MATLAB, e. Haupt-Navigation ein-/ausblenden. Learn more about nan, nansum, multidimentional, array MATLAB Hello, I need to sum some multidimentional arrays after SPMD processing. If my answer helped you can accept it so that others will know that this question has been solved. how many cells in matrix A and matrix B both contain a value. R2022a Update 2 Installation Files can not be used to install a toolbox to R2022a Update 3 MATLAB. nanmean giving nansum output. This MATLAB function returns the sum of the elements of X, computed after removing all NaN values. For matrices, nanmax(A) is a row vector containing the maximum non-NaN element from each column. +100. nansum(a, axis=None, dtype=None, out=None, keepdims=<no value>, initial=<no value>, where=<no value>) [source] #. , 4. Option 1: toolbox free solution using sum and isnan from base MATLAB. However, I have data that needs to be operated. . I want to do a numerical integration of the following equation in Matlab. Show 2 older comments Hide 2 older comments. height=height (~isnan (height)) data=data (~isnan (data)) 4 Comments. " Iniciar sesión para comentar. y is the sum of the non- NaN elements in X. Learn more about plot, sum MATLAB. nansum([1,4, null]) should return 5; other functions; I also would like to add that Matlab, Python (numpy) and R, 3 of the most used programming languages for data science, all deal with nan values by treating them as nan and not by ignoring them by default. y = nansum(X,vecdim) returns the sum over the dimensions specified in the vector vecdim. For multidimensional arrays X, nanmedian operates along the first. So threshold the image to find bad pixels and replace only those like. If you do not specify k, symsum uses the variable determined by symvar as the summation index. In my nested loop format I run through every column of B for each row of A. example. Use hold on to add a second plot to the axes. Learn more about matlab function MATLAB function 'nanmean' is behaving like nansum and I don't know why. Sign in to comment. y = nanstd (X,flag) returns the standard deviation of X based on the normalization specified by flag. You need to use your organization email address in your MathWorks Account to link to the license. Copy. See the bottom of this answer for. DIM: B = nancumsum (A, DIM) returns the nan-cumulative sum of the elements. 関数 nansum は推奨されません。代わりに、MATLAB 関数 sum を使用してください。nansum が削除される予定はありません。 コードを更新するには、関数名 nansum のインスタンスを sum に変更します。次に、入力引数 nanflag に 'omitnan' オプションを指定します。 有时候，在处理数据时，需要对数据求和、平均、标准偏差，但是数据中含有nan时，就比较恼火。Matlab中自带的函数nansum（求和）、nanmean（平均）、nanstd（标准偏差），在去nan数据的情况下，就可以完成求和、平均、标准偏差的操作。 Description. numpy. Task Removed Functionality Use This Functionality; Merge multiple time series objects: merge(fts1,fts2) [TT1;TT2] (requires variable name to be the same) or var or mean) using only the non-NaN values. I want a nan to be returned if there is a nan value present in the grouping. Option 1: toolbox free solution using sum and isnan from base MATLAB. you cannot install a toolbox for MATLAB R2022b into MATLAB R2023a. shape[0] is 2, maximum(a[0], a[1]) is faster than max(a, axis=0). Problem with variable 'nanmean'. Also, using nansum() is not recommended as you can see from its documentation page. Really, it is. timetable 是一种特定类型的表，其中每一行关联一个时间。与表一样，时间表存储具有不同数据类型和大小的列向数据变量，只要它们具有相同的行数即可。此外，时间表提供了特定于时间的函数，可对一个或多个时间表中的带时间戳的数据进行对齐、合并，以及执行计算。Designed for the way you think and the work you do. Learn more about TeamsSorted by: 26. This function enhances the functionality of NANMAX as distributed in the MATLAB Statistics Toolbox and is meant as a replacement (hence the identical name). If you do not specify k, symsum uses the variable determined by symvar as the summation index. If fact NANMAX simply rearranges the input arguments to MAX because MAX already ignores NaNs. Sign in to answer this question. array(a, mask=np. Ralph Andrews on 13 Feb 2023. float64) Note: dtype is the data type of the sum output. 0. nansum(arr, axis=None, dtype=None, out=None, keepdims=’no value’) 参数 : arr :[array_like] 包含数字的数组，其总和是需要的。如果arr不是一个数组，将尝试进行转换。 y = nansum(X,vecdim) returns the sum over the dimensions specified in the vector vecdim. Edit: Another way of achieving this as @rayryeng suggested in the first comment is to use isnan: A (isnan (A))=0 B (isnan (B))=0 C=A+B. Syntax. ) didn't install correctly, were they not included in R2011a, or do they exist under a new name? Thanks! downsample_ts. Perhaps it is not precise to use np. It can be the cumulative sum of the flattened array, the cumulative sum of the array elements along the rows or the cumulative sum of the array elements along the. Example. Precedence of AND and OR Operators. As it can be expected there are a lot of NaN values. Cell Arrays Since matrices can only hold one type of data (numeric or character), cell arrays were introduced in Matlab 5 to allow a single object to contain di erent modes of data. But is there a quick way to achieve that, like nansum in MATLAB, without looping the entire array, removing the NaN and then computing the sum? javascript Sharenumpy. Show -1 older comments Hide -1 older comments. function s = mbNonNan (x) arguments x (1,:) double {mustBeNonNan} end n = length (x); m = sum (x)/n; s = sqrt (sum ( (x-m). Matlab中自带的函数nansum（求和）、nanmean（平均）、nanstd（标准偏差），在去nan数据的情况下，就可以完成求和、平均、标准偏差的操作。 值得注意的是，这几个函数只能求整体的和、平均、标准偏差，局部的和、平均、标准偏差仍然需要自己编程。Using '0's' in place of NAN is fine for operating on, but when I use '0' for plotting, MATLAB thinks '0' is a value and fills in with color. e. For vectors, nanmax(a) is the largest non-NaN element in a. The function computes the means after removing NaN values. ". I need to devide vector by vector, ignoring elements with zero in the denominator. y = nanmedian(X) is the median of X, computed after removing NaN values. B: Output cumulative product matrix,. For example, if X is a matrix, then nansum(X,[1 2]) is the sum of all non-NaN elements of X because every element of a matrix is contained in the array slice defined by dimensions 1 and 2. The function computes the sums after removing NaN values. In probability theory, the sum of two independent random variables. Missing data (or NaN's in matrices) is sometimes a big problem. For matrices X, nanmedian(X) is a row vector of column medians, once NaN values are removed. Edited: Stephen23 on 5 Jan 2016. . As the documentation told you, it's obsolete. The function computes the sums after removing NaN values. y = nanmean(X,vecdim) returns the mean over the dimensions specified in the vector vecdim. Description. Sign in to comment. nan, a) # Set all data larger than 0. To test if an element is NaN, use the function isnan . If installing the toolboxes offline, the installation files must match the update version of MATLAB, e. Example #1. Return the cumulative product of elements along a given axis. (This, of course, was before “Machine. The integral of the output sums to 1. nansum. m at develop · mtex-toolbox/mtexJ = imdilate (I,SE) dilates the grayscale, binary, or packed binary image I using the structuring element SE. (j,k) ) 我想让它使用nansum 我想用0替换nan，然后进行乘法是可能的，但拥有nansum的目的是为了避免这种情况，对吗？乘法产生nan的原因是没有一种真正的方法来处理它们。如果，在您的情况下，它们应该被零替换，那么最容易. The function computes the sums after removing NaN values. numpy. Accepted Answer: Andrei Bobrov. Hello, I am reciving a message from MATLAB saying that 'nansum' use is not reccomended and to use 'sum' instead, with the appropriate code changes. For more information, see nansum. m calculates the standard error of the mean ignoring NaNs. nansum) The code snippet is as follows: abs_matrix = np. The default Matlab nansum. Copy. xlsx attached) that will contain the 7 columns I want to assess, and each column will have saved the positions where a NaN was detected. Find more on Data Import and Analysis in Help Center and File Exchange. y = nanstd (X,flag) returns the standard deviation of X based on the normalization specified by flag. 3 comentarios. g. % M = NANMEAN (X) returns the sample mean of X, treating NaNs as missing. When I type >>help nansum in the command window, matlab returns "nansum not found. The nansum () method in NumPy is a function that returns the sum of the array elements calculated by treating the NaN values in the array as equal to 0. I have implemented a leaky integrate and fire neuron system that gives output in the form of an alpha function alpha = t/tau * exp (1 - (t/tau)). Note there are no inputs here, but your code expects (and requires) the input DataFolder. Use the MATLAB function min instead. nansum(v1*v2) Sample run - In [109]: v1 Out[109]: array([ 1. I think this choice is a big mistake. gitignore","contentType":"file"},{"name":"O2sol. Perhaps it is not precise to use np. ExamplesDesigned for the way you think and the work you do. Traducir. If all values are NaN, the mean is returned as NaN. m","path":"O2sol. In MATLAB = is used only to assign a value. the code is below, it is a homogeneous transformation matrix code for a robot. y = nansum(X,vecdim) returns the sum over the dimensions specified in the vector vecdim. . However, I have data that needs to be operated. J = imdilate (I,nhood) dilates the image I, where nhood is a matrix of 0 s and 1 s that specifies the structuring element neighborhood. nansum for financial time series. For the columns B to H I would like to find NaN values for each co. See syntax, description, input and output. {"payload":{"allShortcutsEnabled":false,"fileTree":{"":{"items":[{"name":"calendar","path":"calendar","contentType":"directory"},{"name":"cm_and_cb_utilities","path. % If your channel is private, then enter the read API Key between the '' below: % Get Output Liquid Quantity data for the last 30. 3 comentarios. g. Returns the discrete, linear convolution of two one-dimensional sequences. But this can be changed, and it can be set individually for different kinds of exceptions. nansum, nanmean etc. Mean ignoring NaNs. 值 得注意的是，这几个函数只能求整体的和、 平均 、标准偏差，局部的和、 平均 、标准偏差仍然需要自己. baidu 【Matlab】matlab软件教学视频+常用函数教学视频（含课件） 【课件在公众号：一朵小白】. What are the options for those of us that want a simple nanmean function? Somewhere I remember seeing an alternative function in Base but I haven’t been able to find it again. First I randomly sample 2 images to get 2 vectors and try to locate the element position of the vector in the original image. Don’t use min for element-wise comparison of 2 arrays; when a. y = nansum(X,vecdim) returns the sum over the dimensions specified in the vector vecdim. function cx_value = cx( alpha, el ) A = [ -0. 2 Answers Sorted by: 3 You can achieve this without using any specific function call just by setting the NaNs to 0s and then performing the sum: A (A~=A)=0 B. you cannot install a toolbox for MATLAB R2022b into MATLAB R2023a. symsum (f,k, [a b]) or symsum (f,k, [a; b. The function computes the sums after removing NaN values. If you are you used to 255 color values from HTML for example, you can divide by 255 to get a value between 0 and 1. As others have pointed out, gray is the result of the Red, Green, and Blue are equal somewhere between 0 and 1 where black is [0 0 0] and white is [1 1 1]. Learn more about nan, nansum, multidimentional, array MATLAB Hello, I need to sum some multidimentional arrays after SPMD processing. y = nansum(X) is the sum computed by treating NaNs as missing values. nansum. . If X is a matrix, then nanmean(X) is a row vector of column means, computed after removing NaN values. Steven Lord on 4 Nov 2016. nansum (a, axis=None, dtype=None, out=None, keepdims=<no value>, initial=<no value>, where=<no value>) [source] # Return the sum of array elements over a given axis treating Not a Numbers (NaNs) as zero. I want to calculate the monthly mean for each year and then calculate average for 10 years. For example, if X is a matrix, then nansum(X,[1 2]) is the sum of all non-NaN elements of X because every element of a matrix is contained in the array slice defined by dimensions 1 and 2. Find the treasures in MATLAB Central and discover how the community can help you! Start Hunting!Why I am getting sum =NaN. We will see the examples for each of these in the. Improve this answer. The default is to 'warn' for invalid, divide, and overflow and 'ignore' for underflow. Made for data-oriented projects in general; Open-source; Handles big data (very large datasets) Large number of ready-made packages; Built-in ways to professionally visualize data{"payload":{"allShortcutsEnabled":false,"fileTree":{"":{"items":[{"name":". Tên của các file và hàm phải giống nhau. nanmean# numpy. How about this: cellfun(@(x) nansum(x,ndims(x)+1), raw_data, 'UniformOutput', false) Note if you're certain you'll only have 2D matrices in raw_data you can replace the ndims(x)+1 with 3. Classic HTML gray is [128, 128, 128]. This MATLAB function returns the sum of the elements of X, computed after removing all NaN values. sum. However, the question is why Matlab has decided to treat NaNs in a certain way in some functions, e. The function computes the sums after removing NaN values. You can mask your array using the numpy. nansum for financial time series objects is based on the Statistics and Machine Learning Toolbox™ function nansum. SO2gm3)); outij =. the imputation of missing values in incomplete datasets. The data set has some missing values as well. Python numpy. Skip to content. 如果 A 是矩阵，则 sum(A) 将返回包含每列总和的行向量。. k = find (X) returns the indices of the array X that point to nonzero elements. Connect and share knowledge within a single location that is structured and easy to search. Which is the mean of a matrix after removing NaN values? The function computes the means after removing NaN values. . Example m = magic (3); m ( [1 6 8]) = [NaN NaN NaN] m = NaN 1 6 3 5 NaN 4 NaN 2 nsum = nansum (m) nsum = 7 6 8 See Also nanmax, nanmin, nanmean, nanmedian, nanstd Version History. 0 Comments. Becasue that also would not work. I don't seem to be able to do it using the function nanmean, since that doesn't sum element per element. 016 0. Learn more about matlab array sum find MATLAB. I can suggest a way to do it using CELLFUN, but I can't guarantee that it will be faster for your problem (you would have to time it yourself on the specific data sets you are using). You can achieve this without using any specific function call just by setting the NaNs to 0s and then performing the sum: A (A~=A)=0 B (B~=B)=0 C=A+B. nansum() as well. e. nansum()函数用于计算一个给定轴上的数组元素的总和，将非数字（NaNs）视为零。. Get absolute value of elements in Numpy matrix (using np. nansum() as well. By default the input is flattened. In MATLAB = is used only to assign a value. Birdman on 13 Feb 2018. hist3 (X,'Nbins',nbins) specifies the number of bins in each dimension of the histogram. Melden Sie sich bei Ihrem MathWorks Konto an;nansum是Matlab概率统计函数的第34集视频，该合集共计59集，视频收藏或关注UP主，及时了解更多相关视频内容。 公开发布笔记 首页{"payload":{"allShortcutsEnabled":false,"fileTree":{"matlab":{"items":[{"name":"QU_KEMAR_AKGK601_hcomp. I want to remove all the elements where there is 0 in the denominator for the operation. Learn more about matlab, sum, nan . Learn more about nansum, function, monthly_sum MATLAB I use the function below to perform the monthly precipitation accumulator, however, when there are days without NaN measurements in a given month, the result for that month is zero. {"payload":{"allShortcutsEnabled":false,"fileTree":{"":{"items":[{"name":"calendar","path":"calendar","contentType":"directory"},{"name":"cm_and_cb_utilities","path. Package: nan. Copy. The flag is 0 (default) or 1 to specify normalization by n – 1 or n, respectively, where n is. As explained on github, accumarray now supports nan-prefixed functions (e. Learn more about nansum . m: 1261: nanvar. I guess the reason for the NaN-in NaN-out behaviour of many functions in Matlab (such as sum, std, mean, median, corrcoef, detrend) is thatBy default, nanstd normalizes y by n – 1, where n is the number of remaining observations after removing observations with NaN values. The function computes the sums after removing NaN values. Share. Cách viết hàm trong MATLAB. Mostrar 2 comentarios más antiguos Ocultar 2 comentarios más antiguos. For matrices, nansum(X) is a row vector containing the sum of the non-NaN elements in each column of X. nanstd (arr, axis = None, dtype = None, out = None, ddof = 0, keepdims) Parameters : arr : [array_like] Calculate the standard deviation of the non-NaN values. example. You can set the regression. To ignore NaN values (MATLAB behavior), please use nanmax. If A is a multidimensional array, then sum (A) operates along. along the dimension of A specified by scalar DIM. Use manual mode to maintain the current x-axis limits when you add more plots to the axes. Show 3 older comments. The question have sort of already been answered before here, but I can seem to get the suggestion to work:. Copy. 099 -0. If you just want to find the length of the column (not including nan entries), here's an example:nansum() is an older routine that is part of the Statistics Toolbox. However, I run into problems with 0 values. ". So far I have done this for column B: Theme. 2. If X is a matrix, then nanmean(X) is a row vector of column means, computed after removing NaN values. y = nansum(X,vecdim) returns the sum over the dimensions specified in the vector vecdim. for i = 1 : size(x,1) for j = 1 : size(x,2) if x(i,j) ~= 0. NANSUM is included to fix a bug in some other versions. Return the sum of array. But removing nanmean, nansum, nanstd, etc from the basic Matlab was a serious mistake. Modified 6 years, 1 month ago. the help command (image below) is also referencing nansum's functionality. shape[0] is 2, maximum(a[0], a[1]) is faster than max(a, axis=0). % in Natick, Massachusetts. Hi Sara, here is an available function for detrending with NaNs. You can't remove them because it would change the size of the matrix. I have added an explanation and numpy implementation. nansum 은 권장되지 않습니다. The sum () function returns NaN if there are NaNs in your array, if that behavior is what you want. Steven Lord on 4 Nov 2016. so I thought you use nanmean and nansum to ignore nans with grpstats, but it seems that it always ignores them. ¶. for lambda=280:2500 numerator (lambda) = trapz (Einc (lambda:lambda+1)*St (lambda)); denominator (lambda) = trapz (Eref (lambda:lambda+1)*St (lambda)); end. 1. For example,nancumsum (A,1) works down the columns, nancumsum (A,2) works across the rows. nansum是【Matlab】matlab软件教学视频+常用函数教学视频（含课件）的第144集视频，该合集共计313集，视频收藏或关注UP主，及时了解更多相关视频内容。. We can use np. The Wilcoxon rank sum test is equivalent to the Mann-Whitney U-test. Open the Curve Fitter app by entering curveFitter at the MATLAB ® command line. These variants basically discard ignore nan values when performing calculations. If A is a matrix, then sum (A) returns a row vector containing the sum of each column. Learn more about matlab function MATLAB function 'nanmean' is behaving like nansum and I don't know why. You can see that in the example, for me nansum(f(:)) = 7. In later versions zero is returned. NANMAX (A,DIM) calculates the maximum of A along the dimension DIM of the N-D array X. Home; Download; Documentation; Videos; Examples; Workshops; Functions ; Geometry. y = nanstd(X) is the standard deviation computed by treating NaNs as missing values. Mostrar 2 comentarios más antiguos Ocultar 2 comentarios más antiguos. Các biểu tượng &, |, và - là các toán tử mảng logic AND, OR, và NOT. Also, using nansum() is not recommended as you can see from its documentation page. The function computes the means after removing NaN values. numpy. I would like to calculate the ensemble time average of these martices using with nanmean function. the help command (image below) is also referencing nansum's functionality. If A is a nonempty matrix, then prod (A) treats the columns of A as vectors and returns a row vector of the products of each column. ma. For example, if A is a matrix, then sum (A, [1 2]) returns the sum of all elements in A because every element of a matrix is contained in the array slice defined by dimensions 1 and 2. NANSUM same as SUM but ignores NaN's. Syntax. 8 Nan is returned for slices that are all-NaN or empty. Show 2 older comments Hide 2 older comments. where in this case matrix is a 1X2 matrix (mine is a lot larger). DIM: B = nancumsum (A, DIM) returns the nan-cumulative sum of the elements. example. If my answer helped you can accept it so that others will know that this question has been solved. Tags ' nullify the effect of nan in mat files' Community Treasure Hunt. The basic idea of matrix multiplication is to sum the products of the rows of matrix A [sza [0], sza [1]] by the columns of B [szb [0], szb [1]], where sza [1] = szb [0]. Then do the grouped calculation, and convert the grouping variable's unique values back to datetime: Theme. You can see this by typing edit nansum. For matrices, nanstd(X) is a row vector containing the standard deviations of the non-NaN elements in each column. .