PlanMaker MUNIT: Dynamic Identity Matrices and Spill Checks
MUNIT creates a square identity matrix in PlanMaker 2026. Use a single-cell dynamic formula, inspect spill obstructions and verify matrix multiplication controls.
Verification status: See the evidence and test scope described in this guide. How formula examples are checked
MUNIT creates a square identity matrix in PlanMaker 2026. Use a single-cell dynamic formula, inspect spill obstructions and verify matrix multiplication controls.
Availability and evidence
The PlanMaker 2026 reference documents MUNIT, and SoftMaker explicitly lists it among the new PlanMaker features in SoftMaker Office Professional 2026. This establishes the announced 2026 introduction release, not an exact first working build or the earliest subscription NX rollout. Equivalent function pages in the checked 2024 and 2021 URL locations returned 404; those earlier manual families are not claimed as supported.
References were retrieved on October 15, 2026. No native PlanMaker execution was performed. Examples below are independently calculated expectations, not application screenshots or native results. FreeOffice/mobile edition coverage and file transfers are not certified. English formulas use commas; verify separators and names in your installation.
Exact syntax and dynamic result
=MUNIT(Dimension)
Dimension is an integer greater than zero. The result has Dimension rows and Dimension columns, with ones on the main diagonal and zeroes elsewhere. The manual states #VALUE! for a dimension that is not greater than zero; it does not establish how fractional dimensions are coerced, so use explicit positive integers.
MUNIT is specifically documented as having a dynamic output range. Enter the formula in one cell and press Enter. PlanMaker expands the result into adjacent cells and updates its size when Dimension changes. If content blocks the required area, the documented error is #SPILL!.
This entry method is function-specific. The same manual still instructs users of MINVERSE and MMULT to enter an array formula through the older selected-range workflow. Do not transfer that instruction blindly to MUNIT, or assume every older array function now spills.
Complete identity-matrix worksheet
On a fresh sheet IdentityControls, leave E1:G3 empty. Put Dimension in A1 and 3 in B1. Enter =MUNIT(B1) in E1 and press Enter. The expected output is:
| Cell row | E | F | G |
|---|---|---|---|
| 1 | 1 | 0 | 0 |
| 2 | 0 | 1 | 0 |
| 3 | 0 | 0 | 1 |
These row labels describe worksheet positions; do not type a header over E1, because E1 is the formula’s anchor. The 3×3 result contains nine numeric cells, not one text string with nine characters.
In a copy change B1 to 2. The expected dynamic result is the 2×2 identity in E1:F2, with rows 1,0 and 0,1. For B1=1, the result is just 1 in E1. Do not fill independent copies of MUNIT into the cells that belong to its output area.
Reproduce the spill obstruction deliberately
On a separate fresh sheet, put the text occupied in B2, then enter =MUNIT(3) in A1. B2 lies inside the intended A1:C3 output, so the documented expectation is #SPILL! at the formula. Clear the blocking content and re-evaluate the formula; the intended mathematical result is the 3×3 identity.
The example uses ordinary cell content, exactly the obstruction covered by the reference. Merged cells, protected sheets, table boundaries and other spill restrictions were not tested and are not assigned invented native behavior here. A visually blank cell may still contain a formula; inspect actual contents when diagnosing a blocked region.
Advanced: verify the matrix identity property
Put the following numeric matrix in J1:L3 on IdentityControls, separately from the spill area:
| Cell row | J | K | L |
|---|---|---|---|
| 1 | 2 | 3 | 1 |
| 2 | 0 | 4 | 5 |
| 3 | 7 | 1 | 6 |
For a multiplication control, set B1 back to 3. Select N1:P3, enter =MMULT(J1:L3,E1:G3) and complete it using the documented array-formula workflow, Ctrl+Shift+Enter on desktop. The independent expected output is exactly the J1:L3 matrix. Right multiplication by a matching identity preserves every element.
For the reverse order, use a separate 3×3 selected output and =MMULT(E1:G3,J1:L3). It has the same expected values. This property is why the identity matrix is the multiplicative neutral matrix; it does not mean general matrix multiplication is commutative.
Advanced: distinguish identity from an all-ones matrix
For the numeric matrix above, an all-ones 3×3 right factor would make each output row repeat that input row’s sum: 6,6,6; 9,9,9; and 14,14,14. MUNIT instead contains only three ones, on the diagonal. Replacing zeroes with ones changes the operation fundamentally.
The determinant of an identity matrix is one, while its diagonal sum equals its dimension. For the 3×3 control, =MDETERM(E1:G3) has expected result 1, and =E1+F2+G3 gives 3. These distinguish two properties that should not be confused.
Errors and verification limits
Zero and negative dimensions violate the documented positive-size condition. A noninteger size is outside this guide’s controlled inputs; no rounding rule is borrowed from another product. Maximum dimensions, memory limits, localized error spellings and mobile entry behavior remain unverified.
When the output is missing or clipped, first check the anchor, the dimension and the required empty square. Confirm that the installed version actually includes MUNIT. The 2026 introduction evidence is narrower than a claim that every older PlanMaker or FreeOffice release supports the function.