# Formula vs Formula2

Range.Formula and Range.Formula2 are two different ways of representing the logic in the formula. They can be thought of a 2 dialects of Excel's formula language.

Excel has always supported two types of formula evaluation: Implicitly Intersection Evaluation ("IIE") and Array Evaluation ("AE"). Before the introduction of Dynamic Arrays, IIE was the default for cell formulas, while AE was used everywhere else (Conditional Formatting, Data Validation, CSE Array formulas, etc).

The primary difference between the two forms of Evaluation was how they behaved when a multi celled range (e.g. A1:A10) was passed to a function that expected a single value:

- IIE would choose the cell on the same row or column as the formula. This operation is referred to as "implicit intersection".
- AE would call the function with each cell in the multi celled range and return an array of results. This operation is referred to as "lifting".

When Range.Formula is used to set a cell's formula, IIE is used for evaluation.

With the introduction of Dyanamic Arrays ("DA"), Excel now supports returning multiple values to the grid and AE is now the default. AE formula's can be set/read using Range.Formula2 which supersedes Range.Formula. However, to facilitate backcompatiblity, Range.Formula is still supported and will continue to set/return IIE formulas. Formula's set using Range.Formula will trigger implicit intersection and can never spill. Formula read using Range.Formula will continue to be silent on where Implicit Intersection occurs.

Range.Formula effectively reports what would be presented in the formula bar in Pre-DA Excel, while Range.Formula2 reports the formula reported by the formula bar in DA Excel.

Excel automatically translates between these two formula variations, so either can be read and set. To facilitate the translation from Range.Formula (using IIE) to Range.Formula2 (AE), Excel will indicate where implicit intersection could occur using the new implicit intersection operator @. Likewise, to facilitate the translation from Range.Formula2 (using AE) to Range.Formula (using IIE) Excel will remove @ operators that would be performed silently. Often there is no difference between the two.

## Translating from Range.Formula to Range.Formula2

This example shows the outcome of setting Range.Formula and then retrieving Range.Formula2

```
Dim cell As Range
Dim str As String
Set cell = Worksheets("Sheet1").Cells(2, 1)
ArrayOfFormulas = Array("=SQRT(A1)", "=SQRT(A1:A4)")
For i = LBound(ArrayOfFormulas) To UBound(ArrayOfFormulas)
cell.Formula = ArrayOfFormulas(i)
str = "Wrote Range.Formula:" & vbCr & cell.Formula & _
vbCr & vbCr & _
"Read Range.Formula2:" & vbCr & cell.Formula2
MsgBox (str)
Next i
```

Write Range.Formula | Read Range.Formula2 | Notes |
---|---|---|

=SQRT(A1) | =SQRT(A1) | Identical because no implicit intersection could occur |

=SQRT(A1:A4) | =SQRT(@A1:A4) | SQRT expects a single value but is given an multi celled range. This will trigger implicit intersection in IIE, therefor the translation to AE calls out where implicit intersection could occur using the @ operator |

## Translating from Range.Formula2 to Range.Formula

Formula set using Range.Formula2 Excel use AE. On file save, DA Excel examines the formulas in the workbook to determine if they would calculate the same in AE and IIE. If they do, to improve backcompatibility, Excel may save it as an IIE to reduce the number of Array formulas seen by Pre DA versions of Excel. You can test whether the formula will be saved to file as an array formula using Range.SavedAsArray()

```
Dim cell As Range
Dim str As String
Set cell = Worksheets("Sheet1").Cells(2, 1)
ArrayOfFormulas = Array("=SQRT(A1)", "=SQRT(@A1:A4)", "=SQRT(A1:A4)", "=SQRT(A1:A4)+SQRT(@A1:A4)")
For i = LBound(ArrayOfFormulas) To UBound(ArrayOfFormulas)
cell.Formula2 = ArrayOfFormulas(i)
str = "Wrote Range.Formula2:" & vbCr & cell.Formula2 & _
vbCr & vbCr & _
"Read Range.Formula:" & vbCr & cell.Formula & _
vbCr & vbCr & _
"Read Range.IsSavedAsArray:" & vbCr & cell.SavedAsArray
MsgBox (str)
Next i
```

Write Range.Formula2 | Read Range.Formula | Read Range.SavedAsArray | Notes |
---|---|---|---|

=SQRT(A1) | =SQRT(A1) | FALSE | SQRT expects a single value, A1 is a single value. Therefor no variance between IIE and AE. Save as IIE and remove any @'s |

=SQRT(@A1:A4) | =SQRT(A1:A4) | FALSE | SQRT expects a single value, @A1:A4 is a single value. Therefor no variance between IIE and AE. Save as IIE and remove any @'s |

=SQRT(A1:A4) | =SQRT(A1:A4) | TRUE | SQRT expects a single value, A1:A4 is a multicell range. IIE and AE could vary therefor save as array |

=SQRT(A1:A4)+ SQRT(@A1:A4) | =SQRT(A1:A4)+ SQRT(@A1:A4) | TRUE | The first SQRT expects a single value, A1:A4 is a multicell range. IIE and AE could vary therefor save as array |

## Best Practice

If targeting DA version of Excel, you should use Range.Formula2 in preference to Range.Formula.

If targeting Pre and Post DA version of Excel, you should continue to use Range.Formula. If however you want tight control over the appearance of the formula the users formula bar, you should detect whether .Formula2 is supported and, if so, use .Formula2 otherwise use .Formula

## Notes

OfficeJS does not include Range.Formula2. Instead Range.Formula always reports what is present in the formula bar. As a newer language with the ability for addins to quickly deploy updates, developers are encouraged to update their addins if they encounter any compatibility issues between AE to IIE.

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