SUMXMY2 in ONLYOFFICE: Sum of Squared Differences

ONLYOFFICE’s SUMXMY2 reference calls this a math-and-trigonometry function and documents:

=SUMXMY2(array_x, array_y)

Exactly two arguments are documented. The order is array_x, then array_y; swapping the two arrays leaves the mathematical result unchanged. The reference does not specify optional arguments, blank/text coercion, numeric precision or explicit shape-error codes. Example formula notation uses English function names and comma-separated arguments.

Open a blank workbook, use English formula language for these examples, and put the following numeric values in A1:B6. The extra C–E columns below show independently calculated row-level checks; they are not input requirements.

A1: x, B1: y. Enter each row’s A and B numbers exactly as shown (including the negative and decimal values):

For a row-level verification, type =A2^2-B2^2 in C2, =A2^2+B2^2 in D2, and =(A2-B2)^2 in E2. Fill these formulas down through row 6. Compare each cell against the expected row above. Using ordinary numeric cells avoids undocumented text-conversion behavior. The formula result is expected mathematically, not a result observed in ONLYOFFICE.

1. Select a blank result cell G2 outside columns A–E.
2. Enter =SUMXMY2(A2:A6,B2:B6) using the exact order shown; press Enter (or use the Formula tab’s documented Insert Function dialog).
3. The independent mathematical expectation is 58 for these five pairs.
4. For a transparent check, use the applicable C, D or E row-calculation column from the table and sum those five cells. That check uses ordinary operators and the arithmetic results shown; it does not assert a vendor-tested equivalence.
5. Try the partial-range, swapped-array and same-array tests in the table below. Each formula uses two same-shaped input ranges.

Squared error and paired distances. If column A holds predictions and column B holds observations in the same row, each squared error is (prediction − observation)². For the demonstration, the row contributions are 1, 49, 4, 0, 4, totaling 58. Reversing the two arrays does not change the result because squaring removes the sign.

Advanced: mean squared error (MSE). With five complete numeric pairs, =SUMXMY2(A2:A6,B2:B6)/COUNT(A2:A6) has expected value 11.6. This assumes COUNT(A2:A6)=5 and that every A value has exactly one matching numeric B value. It is not a sample variance estimate.

Advanced: root mean squared error (RMSE). =SQRT(SUMXMY2(A2:A6,B2:B6)/COUNT(A2:A6)) has independently calculated expected value 3.40587727319. RMSE is in the same units as x and y; MSE is in squared units. Decide whether errors should be weighted or normalized before using this unweighted result for model comparison.

Algebraic cross-check. Σ(x−y)² = Σx² + Σy² − 2Σxy. With the same numeric rows, =SUMX2PY2(A2:A6,B2:B6)-2*SUMPRODUCT(A2:A6,B2:B6) has expected result 58. This identity helps distinguish SUMXMY2 from similarly named SUMX2MY2.

The function’s short official help page documents the required dimensions but does not supply an explicit #VALUE!/#NUM! rule for mismatch or atypical cells. Consequently these are test cases to run in ONLYOFFICE, not observed error claims. If a formula returns a different answer, record the exact Desktop/web build, workbook locale, cell types and screenshot in a future validation pass.

• Documentation evidence, not native execution: The current English function catalogue lists the function and links to the signature described above. The documentation is for ONLYOFFICE Docs Spreadsheet Editor; it is not a function-by-function guarantee for every hosted Docs deployment or Desktop Editors version.
• Desktop versus web: The Docs changelog and Desktop changelog are distinct release histories. Checked 2026-10-13 UTC, neither was used to establish the first-supported version of this function. Do not claim a minimum release number or tested parity without controlled execution on named versions.
• Formula locale: The ONLYOFFICE function-entry guide demonstrates English function names, comma-separated arguments, parentheses, and an initial =. The regional settings guide documents configurable formula language, decimal/thousands separators, and region. These examples use English names, commas between arguments, and a dot for decimals. Recheck the user’s formula language and actual separator settings before copying to a localized workbook; no localized execution was performed.
• Workbook formats: The presence of the formula in the help catalogue does not, by itself, verify Excel, Google Sheets, OpenDocument or earlier-format round trips. Avoid assuming that an identical spelling guarantees identical coercion, error codes or calculation precision elsewhere.

• SUMSQ sums squares of supplied numeric inputs and is useful for independent math cross-checks. It has a distinct argument signature.
• SUMPRODUCT multiplies corresponding values and sums products, useful for the algebraic identities shown above. Its own help page explicitly documents treating nonnumeric entries as zero; that rule must not be transferred to SUMXMY2 without separate evidence.
• SQRT finds the square root of a number, useful in RMS calculations; negative-input #NUM! belongs to SQRT’s own documented rule, not to SUMXMY2.
• COUNT counts numeric cells, useful only when observations are paired and complete.

Formula values are independently calculated mathematical expectations. Native ONLYOFFICE Desktop/web execution, localized parsing, undocumented coercion, error propagation and extreme-value precision were not tested.

Official references checked: 2026-10-13 UTC. Native release/edition testing: not performed.