Matrix Multiplication Error in R: non-conformable arguments (2 Examples)


In this article, I’ll illustrate how to deal with the error message “non-conformable arguments” in R when performing matrix multiplication.

Table of contents:

Let’s do this…


Introduction of Example Data

Have a look at the exemplifying data below:

m1 <- matrix(2)                 # Create first data object
m1                              # Print first data object


table 1 matrix error non conformable arguments r


Table 1 illustrates our first data object: A matrix containing only one value.

m2 <- matrix(1:15, nrow = 5)    # Create second data object
m2                              # Print second data object


table 2 matrix error non conformable arguments r


Table 2 shows the second data object: A matrix with five rows and three columns.


Example 1: Reproduce the Error Message – non-conformable arguments

In this example, I’ll explain how to reproduce the error message “non-conformable arguments” in R.

Let’s assume that we want to multiply our two data objects. Then, we might try to execute the following R code:

m1 %*% m2                       # Trying to multiply data objects
# Error in m1 %*% m2 : non-conformable arguments

As you can see, the error message “non-conformable arguments” has been returned to the RStudio console.

The reason for this is that our first data object m1 is a 1×1 matrix.

Let’s see how we can solve this problem…


Example 2: Fix the Error Message – non-conformable arguments

This example explains how to handle the error message “non-conformable arguments”.

To do this, we have to convert our 1×1 matrix to a vector using the as.vector function:

as.vector(m1) * m2              # Converting m1 to vector


table 3 matrix error non conformable arguments r


Table 3 illustrates the result of the previous R syntax.


Video & Further Resources

In case you need further information on the R programming code of this tutorial, you might want to watch the following video of my YouTube channel. In the video, I’m explaining the topics of this tutorial in R:



Furthermore, you might want to have a look at the other R tutorials on my website.


Summary: At this point you should have learned how to avoid the error “non-conformable arguments” in R programming. If you have additional questions, let me know in the comments section below.


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21 Comments. Leave new

  • I attempted to apply lordif to examine gender differences in my measurement. My gender variable is in the first column followed by the 10 items in the measure. Total N = 1057, almost evenly split by gender. I used the following code:

    genDIF <- lordif(Neur_IRT, [ , 1, criterion = 'Chisq', alpha = 0.01

    I received message: unexpected '[' in genDIF <- lordif (Neur_IRT, ["

    • Hey Robert,

      It seems like the specification of the arguments within the lordif function is incorrect. What do you want to specify with the [ ? Furthermore, it seems like a ) is missing at the end of this line of code.


  • hello,my task is Nonnegative Matrix Factorization,i also meet this problem,but in my code,it is all assumption,so i not find specific matrix to solve,so this problem need how to solve?

  • Dear Joachim,

    My Xp and betahatp are as follows(3*2 and 2*1), but I still cannot do Xp*betahatp, could you please help with this? Thank you in advance.
    [,1] [,2]
    [1,] 2 5
    [2,] 3 6
    [3,] 4 7
    [1,] 1.3333333
    [2,] -0.3333333
    Error in Xp * betahatp : non-conformable arrays

    Best regards,

    • Hey Yina,

      Are you looking for the following result?

      Xp <- matrix(2:7, ncol = 2)
      betahatp <- matrix(c(1.3333333, -0.3333333), ncol = 1)
      betahatp * Xp # Reproduce error
      as.vector(betahatp) * Xp # Fix error


  • (my_omg) <- psych::omega(dsse_data,
    nfactors = 4,
    fm = "minres",
    key = c(1, 1, 1, 1, -1, 1, 1, -1, -1, -1, -1, -1, 1, 1, 1, -1, -1, -1, -1, 1, -1, 1, -1, 1, 1, rep(1, 13)),
    poly = TRUE

    hey, I'm receiving the error: Error in diag(key) %*% m : non-conformable arguments

    • Hey Manisha,

      This is difficult to evaluate without seeing the data in dsse_data. Could you illustrate how these data looks like?


  • hello, could you help me
    X <- model.matrix(status~WOE_usia+WOE_penghasilan+WOE_debitrasio+WOE_keluarga+
    data = datascoring.WOE)
    lasso lasso <- lars(x=X,y=datascoring.WOE$status,trace = TRUE)
    LASSO sequence
    Computing X'X …..
    Error in t(y) %*% x : non-conformable arguments

  • Complete the code chunk in the template to write a function my_chol that accepts a square, positive definite matrix and returns the Cholesky Decomposition in the form of a lower triangular matrix. You may not use the built-in chol() and within your function, although you can use them to validate your answers.
    Your code does need to confirm that the input matrix M is square and positive definite.

  • hello sir
    I try to run my programing in r , but there is a problem.
    y<- rnorm(52)

    lm_fit<- lm(y~x1+x2+x3+x4+x5)

    b<- coefficients(lm_fit)

    theta<- b[c("x1","x2","x5")]
    theta1<- cbind(0.007575006 , 0.008085839 ,-0.010551001)

    #long run elasticities
    ph2<- b[2]/(1-b[6])

    cov1 <- matrix(c(-0.00021705,1.61265e-5,-0.0001109,1.61265e-5,0.0030279,-0.0021881,-0001109,
    -0.0021881,0.0020943), nrow = 3 ,ncol = 3)
    std.err<- deltamethod(~x1/(1-x5),theta1,cov1)

    Error in gdashmu %*% cov : non-conformable arguments
    i do not do with this error. can you help me please?

    • Hey Razieh,

      Please excuse the delayed response. I was on a long vacation, so unfortunately I wasn’t able to get back to you earlier. Do you still need help with your question?


  • Hi,
    I hope you can help me with this. I don’t know why I’m getting a non-conformable arrays error. Here is the output
    > A A
    [,1] [,2] [,3]
    [1,] 1 2 3
    [2,] 4 5 6
    > AT AT
    [,1] [,2]
    [1,] 1 4
    [2,] 2 5
    [3,] 3 6
    > B B
    Error: object ‘B’ not found

  • I’m not sure why the code didn’t show. here it is as the code not the output.

    A <- rbind(c(1,2,3),c(4,5,6))
    AT <- cbind(c(1,2,3),c(4,5,6))
    B<- AT*A

  • Do you know how to calculate clustered standard errors for multinomial regression in R? I am using the ‘multinom()’ command, but it does not work well with the ‘Sandwich’ package.

  • hello. i have this function can you please help me fix this error


    generate_results <- function(seed, corstr,rho, n, each) {
    num_simulations <- 1000

    results <- vector("list", num_simulations)

    for (i in 1:num_simulations){
    n_total <- n*each
    para=c(0) <- data_sim(id=rep(1:n,each=each),rho=rho,phi=1,x=cbind(1,runif(length(id))),
    beta=c(0.5,0.5),x_mis=cbind(0,rnorm(length(id))),para,corstr = corstr,
    family = "binary",lag_level = 1)
    mcar_0.05 <- delete_MCAR($data, p=0.05, cols_mis = c(6))
    case1 <- select(mcar_0.05, id, response, '2')
    id <-$id
    response <- factor($response)
    '2' <- as.numeric(case1$'2')

    model <- response ~ case1$'2'

    if(corstr == "independence") {
    Ri <- glmgee(model, id = id, data = case1, family = binomial, corstr = "independence")
    } else if(corstr == "exchangeable") {
    Ri <- glmgee(model, id = id, data = case1, family = binomial, corstr = "exchangeable")
    } else if(corstr == "ar1") {
    Ri <- glmgee(model, id = id, data = case1, family = binomial, corstr = "AR-M", Mv=1)


    ## to extract estimates

    beta_o <- coef(Ri)[1] ##estimate of intercept
    beta_1 <- coef(Ri)[2] ## estimte of "2"

    standard_errors <- sqrt(diag(vcov(Ri)))
    beta_o_rse <- standard_errors[1] ## rse of intercept
    beta_1_rse <- standard_errors[2] ## rse of "2"

    ## extracting p-value
    mull <- 0
    z_stat_betao <- (beta_o – null)/beta_o_rse
    p_value_betao <- 2*(1-pnorm(abs(z_stat_betao))) ## p-value for intercept

    z_stat_beta1 <- (beta_1 – null)/beta_1_rse
    p_value_beta1 <- 2*(1-pnorm(abs(z_stat_beta1)))

    fit11 <- glmgee(model, id = id, data = case1, family = binomial) ## assumes independence
    fit12 <- update(fit11, corstr="Exchangeable")
    fit13 <- update(fit11, corstr="AR-M", MV=1)

    cic <- CIC(fit11, fit12, fit13)
    min_cic <- which.min(cic$CIC)
    corr_cic <- cic$Correlation[min_cic]

    qic <- QIC(fit11, fit12, fit13)
    min_qic <- which.min(qic$QIC)
    corr_qic <- qic$Correlation[min_qic]

    rjc <- RJC(fit11, fit12, fit13)
    min_rjc <- which.min(rjc$RJC)
    corr_rjc <- rjc$Correlation[min_rjc]

    pac <- PAC(fit11, fit12, fit13)
    min_pac <- which.min(pac$PAC)
    corr_pac <- pac$Correlation[min_pac]

    gpc <- AGPC(fit11, fit12, fit13, k = 0)
    max_gpc <- which.max(gpc$AGPC)
    corr_gpc <- gpc$Correlation[max_gpc]

    sgpc <- SGPC(fit11, fit12, fit13)
    max_sgpc <- which.max(sgpc$SGPC)
    corr_sgpc <- sgpc$Correlation[max_sgpc]

    results[[i]] <- list(corr_cic = corr_cic, corr_qic = corr_qic, corr_rjc = corr_rjc, corr_pac = corr_pac,
    corr_gpc = corr_gpc, corr_sgpc = corr_sgpc, beta_o = beta_o,
    beta_1 = beta_1, beta_o_rse = beta_o_rse, beta_1_rse = beta_1_rse,
    p_value_betao = p_value_betao, p_value_beta1 = p_value_beta1)



    ## A

    case2_results <- generate_results(48, "exchangeable", 0.3, 30, 3)

    It was able to replicate and produce some results but along the way, this error has occured
    Error in crossprod(Vi2, Xiw) : non-conformable argument

    and the traceback option has displayed this
    crossprod(Vi2, Xiw)
    score(datas[[i]], beta = beta_old, out = FALSE)
    glmgee(model, id = id, data = case1, family = binomial, corstr = "independence")
    generate_results(50, "independence", 0.3, 30, 3)

    i have to do thousands of simulation for different data and checking this one by one will be impractical. Thank you

    • Hello,

      The error message you provided, Error in crossprod(Vi2, Xiw) : non-conformable argument, suggests that the two matrices or vectors Vi2 and Xiw cannot be multiplied together due to incompatible dimensions. The operation crossprod(Vi2, Xiw) is effectively equivalent to the matrix product t(Vi2) %*% Xiw, where t() is the transpose function.

      Given the traceback, the error is originating from the function score which is being called by glmgee and then your generate_results function.

      In order to solve the issue, for a single iteration, debug the score function and inspect the dimensions of both Vi2 and Xiw just before the crossprod function is called. Then you can see how and why the dimensions are incompatible.



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