A plugin for OnlyOffice Spreadsheet with two tools: NLP Solver for nonlinear optimization and PolyFit for automatic polynomial regression.
As an OnlyOffice user I noticed there was no solver plugin available — so I built one. The solver uses a customized Nelder-Mead implementation (downhill simplex), written in Go and running inside the plugin via WebAssembly.
By now the solver is mature and reliable in practice. It handles nonlinear problems with nonlinear constraints stably and quickly — closing a real gap in the OnlyOffice feature set.
Classical nonlinear optimization. You define a target cell, parameter cells and optional constraints — the solver minimizes the objective function.
Automatic polynomial regression. You provide input columns and a target column; PolyFit systematically tries all polynomial combinations within the defined degree range and returns the formula with the best fit.
Since version 9, OnlyOffice no longer reliably loads plugins installed through its plugin manager. Until that is fixed in the editor, the plugin can simply be placed into the plugin directory directly — three commands and you're done:
/opt/onlyoffice/desktopeditors/editors/sdkjs-plugins
{88fb63f6-cd50-4e4c-bf2f-f2b0d902d05c} into the
plugin folder:
sudo mv '{88fb63f6-cd50-4e4c-bf2f-f2b0d902d05c}' \
/opt/onlyoffice/desktopeditors/editors/sdkjs-plugins/The legacy plugin loader still works through the plugin manager:
Pick the cell containing the formula you want to minimize. This is your objective function — the value the solver will drive as low as possible.
Select the parameter cells — the values the solver is allowed to adjust to find the optimum.
Note: The solver does not use the current values in your parameter cells. Whatever is in them when you press Start is ignored.
You can specify bounds for each parameter. The solver uses them to construct the initial simplex, which helps it find the correct minimum more reliably. Without explicit bounds the defaults are -1.0 to 1.0 — but these are not binding, the simplex may move beyond them.
When enabled, the parameter will
never exceed the bound. For example, enable
StrictMin and set it to 0 to allow only
positive values.
Add constraints to restrict the solution space. Each constraint has min and max values with their own checkboxes.
When enabled, the corresponding bound is enforced. Leave it off if your constraint doesn't need a limit on that side — e.g. if you require a minimum but don't care about the maximum. Internally, undefined bounds are set to ±MaxFloat64.
Both options are enabled by default for convenience.
Choose the number of iterations. More iterations may produce better results on complex, highly nonlinear problems — but also take longer. Click Start to run the optimization.
PolyFit automatically finds the polynomial formula that best describes your data. You provide input columns (Params) and a target column (Target); the algorithm systematically tries all polynomial combinations within the defined degree range and returns the formula with the best fit.
While the standard mode assumes the objective function
f(x1, x2, x3, …) is already known and only its
parameters need to be tuned, PolyFit treats the function itself as
unknown. Both the structure of the polynomial and its
coefficients are fitted.
This is particularly useful when evaluating measurement series for which no theoretical model is available. Once the formula is determined, you can use it without further computation — as an ordinary cell formula.
In the plugin window, switch to PolyFit at the top.
Select the relevant cell ranges in the spreadsheet and assign them using the buttons:
x1, x2, x3, …
y that the polynomial should
approximate
With Use Native, PolyFit talks to a local HTTP service instead of running the WASM build in the browser. This is significantly faster, especially for large datasets or wide search spaces. See Native PolyFit Service below.
The result is a ready-to-use formula you can paste directly into your spreadsheet — for example:
-0.1300·x2⁻¹·x3² + 1.5252·x1²·x3 + …The PolyFit service is a small native program that performs the computation locally. It is significantly faster than the WASM variant and runs alongside the OnlyOffice editor.
nlp-linux-amd64, nlp-windows-amd64,
nlp-darwin-arm64).
nlp or nlp.exe. The
default port is 8081:
./nlp # default port 8081
./nlp 9000 # custom port
The terminal window must stay open while the service is running.
Stop it with Ctrl+C or by closing the
window. A detailed manual including the HTTP API is included in
the ZIP as README.txt.
I'm actively developing this plugin, and your feedback is invaluable. Here's how you can contribute: