# R Error in solve.default() : Lapack routine dgesv: system is exactly singular

In this post you’ll learn how to handle the “Error in solve.default() : Lapack routine dgesv: system is exactly singular” in the R programming language.

The article consists of two examples for the handling of errors. To be more precise, the page is structured as follows:

Let’s just jump right in!

## Example 1: Reproduce the Error in solve.default() : Lapack routine dgesv: system is exactly singular

In Example 1, I’ll show how to replicate the error message in “solve.default() : Lapack routine dgesv: system is exactly singular”.

First, we have to create an example matrix in R:

```my_mat1 <- matrix(1, ncol = 2, nrow = 2) # Create example matrix my_mat1 # Print example matrix``` By running the previous R programming syntax we have constructed Table 1, i.e. a matrix containing only the value 0.

Let’s try to apply the solve function to this matrix:

```my_mat1_solve <- solve(my_mat1) # Try to solve matrix # Error in solve.default(my_mat1) : # Lapack routine dgesv: system is exactly singular: U[2,2] = 0```

As you can see, the previous R code has returned the “Error in solve.default() : Lapack routine dgesv: system is exactly singular”.

The reason for this is that we have tried to solve a system of equations that consists exactly of the same values. This is not possible and for that reason the R programming language returns the error message.

Note that this error can also occur when you have different values in your matrix. However, the error message typically tells that something is wrong with the input matrix.

Typical reason are that a matrix is singular and cannot be inverted or that some vectors are collinear.

So how can we fix this problem? That’s what I’ll explain next!

## Example 2: Fix the Error in solve.default() : Lapack routine dgesv: system is exactly singular

This example shows how to properly apply the solve function to a matrix in R.

For this, we first have to create another matrix:

```my_mat2 <- matrix(1:4, ncol = 2, nrow = 2) # Matrix with different values my_mat2 # Print second matrix``` By running the previously shown R programming syntax we have constructed Table 2, i.e. a matrix that consists of different values.

Let’s apply the solve function to our new matrix:

```my_mat2_solve <- solve(my_mat2) # Solve matrix my_mat2_solve # Print solved matrix``` After running the previous syntax the matrix revealed in Table 3 has been created. As you can see, the application of the solve function worked fine.

## Video & Further Resources

If you need further information on the R code of this tutorial, you may want to watch the following video of my YouTube channel. I show the examples of the present page in the video:

In addition, you might have a look at the other articles of this homepage. You can find a selection of tutorials below.

This tutorial has shown how to avoid the “Error in solve.default() : Lapack routine dgesv: system is exactly singular” in the R programming language. In case you have additional questions, let me know in the comments.

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