# Excel Array Matrix Operation

In Excel, we have a built-in function used to perform matrix operations. It is the **MMULT function**. This function accepts two arrays as parameters and returns the product of the two arrays. However, this function has a prerequisite that the number of rows and columns of the two arrays passed in are the same.

**MMULT function **is used to calculate the matrix product of two arrays, its syntax structure is as below:

`=MMULT (arrayl, array2)`

where `array1`

, `array2 `

are the two arrays to be multiplied. the number of columns of `array1 `

and the number of rows of `array2 `

must be the same, and both arrays can only contain numeric elements.

## Excel Array Matrix Operation Example

If you have an interview score sheet, you need to score `Secretarial Skills`

, `Interpersonal Skills`

, and `Professional Behavior`

and calculate the final score. The Secretarial Skills, Interpersonal Skills, and Professional Behavior scores are weighted at `0.3`

, `0.5`

, and `0.2`

, respectively.

In order to calculate the final interview scores for each person, you need to perform a matrix product of the skill item scores and the weighted value scores by using the **MMULT function**, which you can refer to the following steps.

**STEP 1#** Select the cell area `G3:G11`

**STEP2#** In the formula bar, enter the following array formula

`=MMULT(D3:F11,I3:I5)`

**STEP3#** Press ** Ctrl+Shift+Enter** shortcut keys to convert the above ordinary formula into an array formula.

`{=MMULT(D3:F11,I3:I5)}`

From the screenshot above, you can see that `TOM `

had the best interview score, his interview score was `4.7`

.

Since the interview results table on the left and the weight table on the right are mutually corresponding, you can use the **MMULT function** to calculate the matrix product of the array of scores and the array of weights to get the final interview results. The **MMULT function **returns an array of results, which must be entered as a multi-cell array formula in order to fill the `G3:G11`

cell area with the results.

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