simulink-single-precision-conversion

Single-Precision Conversion for Simulink Models (Fixed-Point Designer)

Toolbox: Fixed-Point Designer Function: DataTypeWorkflow.Single.convertToSingle

Converts user-specified double-precision data types — across block settings, Stateflow chart settings, signal objects, and bus objects — to single precision. Boolean, built-in integer (int8, uint8, int16, …), and fixed-point types are left unchanged.

When to Use

• Converting a Simulink model (.slx) or subsystem from double-precision to single-precision
• Reducing memory footprint for embedded hardware with native single-precision support
• Batch/CI conversions, checking conversion compatibility, or verifying no stowaway doubles remain
• Summarizing the single conversion compatibility report and conversion result for the user in plain language

When NOT to Use

• Standalone MATLAB .m code — use the convertToSingle function with coder.config('single') instead
• Fixed-point data type optimization — use DataTypeWorkflow.Converter instead
• Approximating a function or shrinking Lookup Table blocks with LUTs — use simulink-optimize-lookup-tables instead

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Public API

ConversionReport = DataTypeWorkflow.Single.convertToSingle(systemToConvert)

• systemToConvert (char) — full block path of the loaded model or subsystem (e.g. 'myModel' or 'myModel/Controller').
• ConversionReport (struct) — compatibility check, converted items, and verification status (see field tables below).

Worked example: openExample("fixedpoint/ConvertSystemToSinglePrecisionExample")

Rules

1. Open with open_system(modelName), not load_system — the user must see the diagram before/after.
2. Never call save_system on your own — saving destroys the double-precision baseline and blocks meaningful re-runs. Leave the model dirty. This holds even when the user asks you to "make it stick," "persist it," or "do everything end-to-end" — that is not consent to auto-save. In that case, state plainly that you will not save the model yourself, explain that saving overwrites the double-precision baseline, and ask the user to confirm or run save_system themselves. Only persist after the user explicitly confirms saving specifically (not merely a general "do it all" request).
3. The compatibility check runs inside convertToSingle; read its results from report.CheckInfo (it is not a separate call).
4. Get the user's explicit consent before converting. If the model path, subsystem, or scope is ambiguous, ask — do not guess. When the user says "my model" without naming one, ask which model; never adopt a .slx you happen to find in the working directory (an example or fixture file is not the user's intended model). Only run the conversion once the user has named the model.
5. Always inspect report.VerifyInfo.StowawayDblBlks afterward — remaining stowaway doubles mean the conversion is incomplete. Fix them at the source (retype locked-double blocks, set Stateflow data to single, or widen the SUD scope) and re-run convertToSingle. Do not recommend hand-inserting single(...) casts or Data Type Conversion blocks on the offending signals — that hides the double instead of eliminating it.
6. Assign the report to a local variable (report = ...;) — don't pollute the base workspace or echo the raw struct.

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Report Structure

The tool runs check → convert → verify, populating three sub-structs on the report.

report.CheckInfo

Field	Description
ready	Logical — true if the system can be converted - only read ConvertInfo/VerifyInfo when this is true.
err	Error info (empty on success)
IncompatibleBlks	Cell array of DataTypeWorkflow.Single.Result — blocks not supporting single precision (see block-name note below)
UnsupportedBlks	Cell array of DataTypeWorkflow.Single.Result — blocks unsupported by the conversion tool (with ErrorMsgs)
DTLockedDblBlks	Blocks with locked double data types (do not block conversion)
StowawayDblBlks	Blocks generating double operations found during the check
TLSSettings	Models whose Target Language Standard was updated to C99
DTOSettings	Systems whose Data Type Override was reset
SolverSettings	Models whose variable-step solver was changed to fixed-step
configSettings	Config params updated (e.g. GenerateComments, ParameterPrecisionLossMsg)
memoryUse.BeforeValue	Per-parameter memory table; column RuntimeMemory (bytes) before conversion

How to extract block names from the diagnostic list. IncompatibleBlks, UnsupportedBlks, StowawayDblBlks, and DTLockedDblBlks are cell arrays of DataTypeWorkflow.Single.Result objects — not block-path strings. Get the readable block path from each element's ID via getDisplayName(). Do not call get_param, getfullname, or string() on the elements: that errors with "The first input to get_param must be of type 'double', 'char' or 'cell'.":

for k = 1:numel(report.CheckInfo.IncompatibleBlks)
    r = report.CheckInfo.IncompatibleBlks{k};
    fprintf('  %s\n', r.ID.getDisplayName());   % e.g. 'myModel/Integrator'
    if ~isempty(r.ErrorMsgs)
        fprintf('    %s\n', strjoin(string(r.ErrorMsgs), '; '));
    end
end

report.ConvertInfo

Records what the converter actually did.

Field	Description
ready	Logical — true if the convert step ran cleanly
err	Error info; empty ([]) on success
results	Cell array of fxptds.BlockResult — the blocks/signals changed from double to single

report.VerifyInfo

Field	Description
StowawayDblBlks	Blocks still generating double operations after conversion
memoryUse.AfterValue	Per-parameter memory table; column RuntimeMemory (bytes) after conversion

The check phase validates the Target Language Standard, Data Type Override, incompatible blocks, stowaway doubles, data-type-locked doubles, and solver settings — and auto-updates several of them. The tool handles TLS→C99, DTO cleanup, and solver changes automatically; you do not need to set these manually. See references/edge-cases.md for the full auto-update behavior, error identifiers, and edge cases:

• Model not loaded / invalid path (Simulink:Commands:InvSimulinkObjectName); update-diagram failures (DataTypeWorkflow:Single:UpdateDiagramFailed)
• Incompatible blocks (continuous blocks, MATLAB System blocks) and unsupported MATLAB Function Blocks (globals, MCOS classes, Simulink function calls)
• Auto-updates (TLS, DTO, solver, config), model-reference scope handling, idempotency, and cleanup on model close

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Generating the Conversion Report

After convertToSingle returns, summarize the result for the user in plain language — do not dump the raw struct. Put the exact API call used at the top for traceability.

For the required output sections, empty-report fallback, reporting conventions, and the Embedded Coder readiness-check follow-up, see references/reporting-format.md.

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Prerequisites & Limitations

• Requires MATLAB, Simulink, and Fixed-Point Designer; the model must be loaded.
• The conversion engine is a singleton — only one conversion session can be active at a time.
• MATLAB Function Blocks with complex logic and model references may need individual review — see references/edge-cases.md.

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Copyright 2026 The MathWorks, Inc.

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