====== Metric Cross Product ======

====Overview====
The Metric Cross Product command is used to create a cross product of two metric vectors. This could include finding the torque acting on a joint or other similar uses. The command can be found within the **Pipeline Workshop** in the **Metric** folder. The command acts on the active files.

====Pipeline Command====

The command, as seen in the pipeline workshop, is below.

<code>
Metric_Cross_Product
! /RESULT_FILE=
! /RESULT_METRIC_FOLDER=PROCESSED
/RESULT_METRIC_NAME=
! /METRIC1_FILE=
! /METRIC1_FOLDER=PROCESSED
/METRIC1_NAME=
! /METRIC2_FILE=
! /METRIC2_FOLDER=PROCESSED
/METRIC2_NAME=
! /DIVIDE_BY_METRIC2_LENGTH=TRUE
! /GENERATE_MEAN_AND_STDDEV=TRUE
! /APPEND_TO_EXISTING_VALUES=FALSE
! /GENERATE_VECTOR_LENGTH_METRIC=FALSE
! /RETAIN_NO_DATA_VALUES=FALSE
;
</code>

====Command Parameters====

The following table shows the command parameters seen above and their descriptions:

|**RESULT_METRIC_NAME**|**The name of the result signal**|
|**RESULT_METRIC_FOLDER**|**The name of the result signal folder**|
|**METRIC1_FILE**|**The movement trial containing the first metric value**|
|**METRIC1_NAME**|**The name of the signal containing the first metric value**|
|**METRIC1_FOLDER**|**The name of the metric signal folder**|
|**DIVIDE_BY_METRIC2_LENGTH**|**(True or False) Divide the resulting signal by the length of the second metric**|
|**GENERATE_MEAN_AND_STDDEV**|**(True or False)Generate the mean and standard deviation for all of the metrics created**|
|**APPEND_TO_EXISTING_VALUES**|**(True or False)Append this list of metrics to an existing metric of the same result name**|
|**GENERATE_VECTOR_LENGTH_METRIC**|**(True or False)Generate metric value for vector length**|
|**RETAIN_NO_DATA_VALUES**|**In cases where there is NO_DATA at an event, you need to specify the parameter /Retain_No_Data_Values=TRUE should you want this included in the resulting signal.**|

====Dialog====
The command can be edited in a text editor or in a dialog form. To edit in the dialog pop up form either click on the **Edit** button in the pipeline workshop or double-click on the pipeline command. The dialog is shown below.

{{:MetricCrossProductDlg.png}}

The dialog box allows you to assign values to the command parameters outlined above.

=== Metric_File ===

If **Metric1_File** or **Metric2_File** are empty, Visual3D uses each active file when processing the command.

These parameters exist because the user may want to compute the dot product relative to a signal in the GLOBAL workspace or a specified file.

=== Divide_By_Metric2_Length ===

When this is true, a unit vector of Metric2 is used.

=== Append_to_Existing_Values ===

The results are concatenated to an existing signal.

====Examples====

===Simple example: Stride Vectors===
Here we use the **Metric Cross Product** command to compute step width from previously calculated stride vectors found using **Metric Vector Between Events**.

The command is as follows:

<code>
Metric_Cross_Product 
! /METRIC1_FILE= 
/METRIC1_NAME=RightStep 
! /METRIC1_FOLDER=PROCESSED 
/METRIC2_FILE=GLOBAL 
/METRIC2_NAME=StrideVectors_MEAN 
! /METRIC2_FOLDER=PROCESSED 
! /DIVIDE_BY_METRIC2_LENGTH=TRUE 
/RESULT_METRIC_NAME=RightStepWidth 
! /RESULT_METRIC_FOLDER=PROCESSED 
! /GENERATE_MEAN_AND_STDDEV=TRUE 
! /APPEND_TO_EXISTING_VALUES=FALSE 
/GENERATE_VECTOR_LENGTH_METRIC=TRUE 
; 
</code>

In the case that you already know or have calculated step length and know the associated stride vectors, the cross product can be used to compute step width.
===Complex example===

For a more in depth example similar to the one above go to [[visual3d:documentation:pipeline:signal_commands:mimicking_temporal_distance_command|this tutorial]].