DP44/enriched-partialglm/DTS Viewer/DTS.Viewer.Modules/DTS.Viewer.AddCalculatedChannel/Model.md

source_files, generated_at, model, schema_version, sha256

source_files	generated_at	model	schema_version	sha256
DTS Viewer/DTS.Viewer.Modules/DTS.Viewer.AddCalculatedChannel/Model/CalculatedChannelCreator.cs	2026-04-16T11:21:42.260506+00:00	zai-org/GLM-5-FP8	1	d05bf6b72e9c97be

Documentation: CalculatedChannelCreator

1. Purpose

The CalculatedChannelCreator class is a static factory that creates derived data channels from existing test data channels. It supports multiple calculation types including aggregate operations (SUM, AVE, Resultant, HIC), binary operations (Integral, DoubleIntegral, Derivative, Sin, Cos), and specialized 3D IR-Tracc sensor calculations. The module handles sample rate alignment via super-sampling, creates persistent memory-mapped file storage for calculated data, and integrates the results back into the test data hierarchy.

2. Public Interface

CreateChannels

public static Test.Module.CalculatedChannel[] CreateChannels(
    string testId,
    string folder,
    Calculation calculation,
    List<Test.Module.Channel> inputChannels,
    string channelName,
    int startingNumber,
    List<Test.Module.Channel> allChannels,
    int clipLength,
    out List<string> errorList,
    int defaultEncoding)

Behavior: Main entry point for creating calculated channels. Routes to appropriate internal creation method based on Calculation type:

• ThreeDIRTracc, ThreeDIRTraccLowerThorax, ThreeDIRTraccAbdomen → Create3DIRTraccChannels
• SUM, AVE, Resultant, HIC → CreateChannelsAggregateOperation
• All others → CreateChannelsBinaryOperation

Returns null if channel name validation fails or calculation produces no results. Sets AbsoluteDisplayOrder on each returned channel starting from startingNumber.

ValidateChannelName

public static bool ValidateChannelName(
    string channelName,
    List<Test.Module.Channel> inputChannels,
    List<Test.Module.Channel> allChannels,
    out List<string> errorList)

Behavior: Validates that the channel name is non-empty and unique across both inputChannels and allChannels. Returns true if valid (empty error list). If allChannels is null, returns true immediately with no validation performed.

ThreeDIRTraccType (nested enum)

public enum ThreeDIRTraccType
{
    Thorax,
    Abdomen,
    LowerThorax
}

Behavior: Specifies the anatomical mounting position for 3D IR-Tracc sensors, which affects calculation constants (δ and D0).

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3. Invariants

1. Channel Number Offset: All calculated channels use ChannelNumberCalculationChannelIndicator (100000) as a base offset added to the provided starting number.

2. 3D IR-Tracc Input Count: Create3DIRTraccChannels asserts that exactly 3 input channels are provided. Failure triggers System.Diagnostics.Trace.Assert.

3. Aggregate Operation Input Count: CreateChannelsAggregateOperation asserts at least 1 input channel is provided.

4. Sample Rate Compatibility: For aggregate and 3D IR-Tracc operations, the maximum sample rate must be an integer multiple of all input channel sample rates. If not, NotSupportedException is thrown.

5. Binary Operations: Only the first channel in inputChannels is used for binary operations (Integral, Derivative, Sin, Cos, etc.).

6. HIC Unit Requirement: HIC calculations require acceleration in g's. If input engineering units are not "g", data is converted from m/s² using factor 9.80665.

7. Super-Sampling Warning: When input channels have different sample rates, a PageErrorEvent is published with SuperSamplingWarning resource string.

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4. Dependencies

This module depends on:

• DTS.Common.Enums.Sensors - SensorConstants for IR-Tracc physical constants
• DTS.Common.Utilities.Logging - APILogger for file operation logging
• DTS.Common.Utils - FileUtils for file deletion
• DTS.Serialization - SliceRaw.File format handling
• DTS.Slice.Control - Test/Event module channel types
• DTS.Common - Constants.ADC_MIDPOINT, ZeroMethodType
• DTS.Common.Events - PageErrorEvent, PageErrorArg
• DTS.Common.Calculations - HeadInjuryCriterion for HIC calculation
• DTS.Common.Utilities.Math.Nhtsa - Integration, Differentiation classes
• Prism.Ioc - ContainerLocator for service resolution
• Prism.Events - IEventAggregator for event publishing

What depends on this module:

• Inferred: AddCalculatedChannelViewModel (referenced via using static for ThreeDIRTraccType context)
• Inferred: Any module calling CreateChannels to generate derived data channels

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5. Gotchas

1. Explicit GC.Collect(): CreatePersistentInformationObject calls GC.Collect() before attempting file deletion to release file handles. This is a heavy operation that may cause performance issues.

2. Unused Variable: In PerformCalculationsAggregate, the variable timeAtIndex is declared and assigned (var timeAtIndex =) but the value is never used—the assignment result is discarded.

3. Debug File Replacement: PerformCalculation (3D IR-Tracc) calls DiskUtility.ReplaceDataIfNeeded with hardcoded filenames ("DISPLEU.txt", "YPOTEU.txt", "ZPOTEU.txt"). This appears to be debug/test instrumentation left in production code.

4. ScaleEuData Scaling Logic: The scaling factor calculation handles bipolar signals by doubling the max value (max *= 2), but the scaleFactor calculation differs based on whether max exceeds short.MaxValue—one path divides, the other multiplies, which may produce unexpected scaling behavior.

5. Null Return on Validation Failure: CreateChannels returns null if ValidateChannelName fails, but the error list is populated via out parameter. Callers must check both the return value and error list.

6. Binary Operations Ignore Additional Channels: CreateChannelsBinaryOperation and PerformCalculationBinary only use inputChannels[0]. Additional channels in the list are silently ignored.

7. HIC-Specific Handling: HIC calculation is performed inside CreateChannelsAggregateOperation after channel creation, setting T1, T2, and HIC properties on the calculated channel. This is not visible from the public method signature.