The MMULT function in Excel 2010


The following tutorial will guide you on how to find the matrix product of two arrays using the MMULT function that is present in Excel 2010 Application.


Description

The function MMULT returns the matrix product of two arrays. The resultant value is also an array and it will be having equal number of rows as array1 and equal number of columns as array2. For example, if array 1 consists of 2 rows and 2 columns and array 2 consists of 2 rows and 3 columns, then the resultant array will have 2 rows and 3 columns.


Syntax

The Syntax of the MMULT function is

=MMULT( array1, array2)

Where

array1 and array2 are required arguments and these are the arrays for which you want to find out the matrix product.


Constraints

The number of columns present in array1 must be the same as the number of rows present in array2.

Both the arrays must contain only numerals.

Both the arrays can be given as cell ranges, references or array constants.

When the number of columns in array1 is not equal to the number of rows in array 2 or any cells in any of the arrays are blank, the MMULT function returns a #VALUE! error value.

The same technique that is used for multiplying two matrices holds good.

The MMULT function that returns an array as the answer should be entered as an array formula.


Example

Refer the figures shown below for examples on MMULT function

Example 1


Figure 1


the figure 2 shows the resultant array of example 1


Figure 2



In the example above, the formula for the MMULT function should be entered as an array formula. i.e. after entering the two arrays and the formula to multiply it, select the cells A9:B10 by dragging the fill handle and press F2 and then press CTRL+SHIFT+ENTER keys together. If the formula is not entered as an array formula, only single value 18 will be displayed.


Example 2


Figure 3


the figure 4 shows the resultant array for example 2


Figure 4


In this example also, the formula for the MMULT function should be entered as an array formula and the cells A10:B12 should be selected by dragging the fill handle, then press F2 and then press CTRL+SHIFT+ENTER keys together.


So, this is how you can find out the matrix product of two given arrays using the MMULT function in Microsoft Excel 2010 application.



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