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visual3d:documentation:pipeline:expressions:mathematical_operators [2024/07/03 17:28] – removed sgrangervisual3d:documentation:pipeline:expressions:mathematical_operators [2024/11/04 20:30] (current) – wikisysop
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 +====== Mathematical Operators  ======
 +
 +The [[visual3d:documentation:pipeline:expressions:expressions_overview|Evaluate_Expression]] command can be used to evaluate arbitrary mathematical expressions. Use the following characters for your mathematical operators. 
 +
 +**Arithmetic Operators** 
 +  * [[#Plus|Plus ]]
 +  * [[#Minus|Minus]]
 +  * [[#Multiply|Multiply]]
 +  * [[#Divide|Divide]]
 +  * [[#Power|Power]]
 +
 +**Boolean Operators** 
 +  * [[#Logical_Or|Logical OR]]
 +  * [[#Logical_And|Logical AND]]
 +  * [[#Using_the_Adjective_NOT|The Adjective NOT]]
 +
 +**Comparison Operators**
 +  * [[#Equals|Equals]]
 +  * [[#Not_Equals|Not Equals]]
 +  * [[#Less_Than|Less Than]]
 +  * [[#Less_Than_Or_Equals|Less Than Or Equals]]
 +  * [[#Greater_Than|Greater Than]]
 +  * [[#Greater_Than_Or_Equals|Greater Than Or Equals]]
 +
 +Note: Visual3D parses the mathematical operators before it parses the signal names. If you have a signal name that contains a mathematical operator (e.g. R-Foot1), Visual3D will probably not be able to parse the equation expression properly.
 +
 +===== Arithmetic Operators =====
 +
 +Arithmetic operations can generally be performed using syntax that is similar to that found in a variety of programming and scripting languages.
 +
 +==== Plus ====
 +
 +Addition is accomplished using the + character. An alternative syntax is **add(a,b)** where a and b are expressions that evaluate to numbers. 
 +
 +NOTE: Pipeline command parameters use the + character as a delimiter. If the user wants to use an expression containing a + in a command parameter that allows multiple signals, then Visual3D will likely interpret this plus sign incorrectly. In this case the **add(a,b)** syntax should be used.
 +
 +<code>
 +2 + 3 = 5
 +add(2,3) = 5
 +</code>
 +
 +==== Minus ====
 +
 +Subtraction is accomplished using the - character.
 +
 +<code>
 +3 - 2 = 1
 +</code>
 +
 +==== Multiply ====
 +
 +Multiplication is accomplished using the * character.
 +
 +<code>
 +3 * 2 = 6
 +</code>
 +
 +==== Divide ====
 +
 +Division is accomplished using the / character.
 +
 +<code>
 +6 / 3 = 2
 +</code>
 +
 +==== Power ====
 +
 +Exponentiation is accomplished using the ^ character.
 +
 +<code>
 +2^3 = 8
 +</code>
 +
 +===== Boolean Operators =====
 +
 +Boolean operators deal with boolean values, such as TRUE and FALSE. These are represented numerically as 1 (TRUE) and 0 (FALSE).
 +
 +==== Logical OR ====
 +
 +The Logical OR operator is signified by the | character. It takes two boolean values as input and returns TRUE if either of the input values is TRUE.
 +
 +<code>
 +FALSE | FALSE = FALSE
 +FALSE | TRUE = TRUE
 +TRUE | FALSE = TRUE
 +TRUE | TRUE = FALSE
 +</code>
 +
 +==== Logical AND ====
 +
 +The Logical AND operator is signified by the & character. It takes two boolean values as input and returns TRUE when both input values are TRUE.
 +
 +<code>
 +FALSE | FALSE = FALSE
 +FALSE | TRUE = FALSE
 +TRUE | FALSE = FALSE
 +TRUE | TRUE = FALSE
 +</code>
 +
 +==== The Adjective NOT ====
 +
 +The logical adjective NOT can be used with both the logical AND and logical OR operators. It takes one boolean value as input and negates that boolean value.
 +
 +<code>
 +NOT(FALSE) = TRUE
 +NOT(TRUE) = FALSE
 +</code>
 +
 +===Example===
 +
 +Given a workspace containing 3 trials (*trial1.c3d, *trial2.c3d, and *trial3.c3d).
 +  * All trials are assigned a TAG labeled WALK
 +  * trial1.c3d is also assigned a TAG labeled BAD
 +
 +<code>
 +Select_Active_File
 +/FILE_NAME=WALK
 +/QUERY=BAD
 +;
 +</code>
 +
 +This command results in *trial1.c3d being active
 +
 +<code>
 +Select_Active_File
 +/FILE_NAME=WALK
 +/QUERY=NOT(BAD)
 +;
 +</code>
 +
 +This command results in *trial2.c3d and *trial3.c3d being active.
 +
 +===== Comparison Operators =====
 +
 +Comparison operators take two inputs of the same type and return a boolean value.
 +
 +==== Equals ====
 +
 +Equality is tested using either = or ==. It returns TRUE if the two inputs have the same value and FALSE if they do not.
 +
 +===Example===
 +
 +Consider a model metric that is defined as a string and compare it to an explicitly defined string.
 +
 +<code>
 +Set_Model_Metric
 +! /CALIBRATION_FILE=
 +/METRIC_NAME=TEST
 +/METRIC_VALUE="TTT"
 +;
 +
 +Evaluate_Expression**
 +/EXPRESSION=MODEL::METRIC::TEST="TTT"
 +/RESULT_NAME=SCOTT
 +/RESULT_TYPE=METRIC
 +! /RESULT_FOLDER=PROCESSED
 +;
 +</code>
 +
 +The text strings are equal, so the resulting signal contains a 1 (indicating TRUE).
 +
 +==== Not Equals ====
 +
 +Non-equality is tested using either <> or ><. Its behaviour is opposite that of equality.
 +
 +If (a==b) is TRUE then (a<>b) is FALSE. Similarly, if (a==b) is FALSE, then (a<>b) is TRUE.
 +
 +==== Less Than ====
 +
 +We can test is one value is less than another using the < character.
 +
 +===Example===
 +
 +Given two signals TARGET::ORIGINAL::RFT1 and TARGET::ORIGINAL::LFT1, use the Boolean operator < to identify when the Z component of RFT1 is less than the Z component of LFT1.
 +
 +<code>
 +Evaluate_Expression
 +/EXPRESSION= TARGET::ORIGINAL::RFT1::Z < TARGET::ORIGINAL::LFT1::Z
 +/RESULT_NAME=RFT1_GREATER
 +/RESULT_TYPE=DERIVED
 +/RESULT_FOLDER=PROCESSED
 +;
 +</code>
 +
 +The output signal will be 1 when RFT1::Z is less than LFT1::Z and 0 otherwise
 +
 +===Example - Foot Clearance===
 +
 +Heel and toe clearance are defined by two paths. It is possible to model "foot clearance" as the lower value of the heel and toe clearance values at each frame.
 +{{:heel_toe_clearance.jpg}}
 +
 +Here is a simplified test of this. First, make the Global Workspace Active. Then, create 2 toy signals and calculate a third signal containing the lower value of the two toy signals.
 +
 +<code>
 +Evaluate_Expression
 +/EXPRESSION=LIST(1,2,3,4,5)
 +! /SIGNAL_TYPES=
 +! /SIGNAL_FOLDER=ORIGINAL
 +! /SIGNAL_NAMES=
 +! /SIGNAL_COMPONENTS=
 +/RESULT_TYPES=DERIVED
 +/RESULT_FOLDERS=PROCESSED
 +/RESULT_NAME=SIGNAL1
 +! /APPLY_AS_SUFFIX_TO_SIGNAL_NAME=FALSE
 +;
 +
 +Evaluate_Expression
 +/EXPRESSION=LIST(5,4,3,2,1)
 +! /SIGNAL_TYPES=
 +! /SIGNAL_FOLDER=ORIGINAL
 +! /SIGNAL_NAMES=
 +! /SIGNAL_COMPONENTS=
 +/RESULT_TYPES=DERIVED
 +/RESULT_FOLDERS=PROCESSED
 +/RESULT_NAME=SIGNAL2
 +! /APPLY_AS_SUFFIX_TO_SIGNAL_NAME=FALSE
 +;
 +
 +!create a new signal that is the lower value of the two signals
 +Evaluate_Expression
 +/EXPRESSION=(DERIVED::PROCESSED::SIGNAL1<=DERIVED::PROCESSED::SIGNAL2)*DERIVED::PROCESSED::SIGNAL1
 ++(DERIVED::PROCESSED::SIGNAL2<DERIVED::PROCESSED::SIGNAL1)*DERIVED::PROCESSED::SIGNAL2
 +! /SIGNAL_TYPES=
 +! /SIGNAL_FOLDER=ORIGINAL
 +! /SIGNAL_NAMES=
 +! /SIGNAL_COMPONENTS=
 +/RESULT_TYPES=DERIVED
 +/RESULT_FOLDERS=PROCESSED
 +/RESULT_NAME=SIGNAL_LOWER
 +! /APPLY_AS_SUFFIX_TO_SIGNAL_NAME=FALSE
 +;
 +</code>
 +
 +{{:heel_toe_clearance2.jpg}}
 +
 +==== Less Than Or Equals ====
 +
 +This boolean operator uses one of the following syntaxes: <= or =<.
 +
 +The expression (a <= b) is equivalent logically to ((a < b) | (a == b)).
 +
 +===Example===
 +
 +Given two signals TARGET::ORIGINAL::RFT1 and TARGET::ORIGINAL::LFT1, use the Boolean operator <= or the boolean operative =< to identify when the Z component of RFT1 is less than or equal to the Z component of LFT1.
 +
 +<code>
 +Evaluate_Expression
 +/EXPRESSION= TARGET::ORIGINAL::RFT1::Z <= TARGET::ORIGINAL::LFT1::Z
 +/RESULT_NAME=RFT1_GREATER
 +/RESULT_TYPE=DERIVED
 +/RESULT_FOLDER=PROCESSED
 +;
 +</code>
 +
 +The output signal will be 1 (indicating TRUE) when RFT1::Z is less than or equal to LFT1::Z and 0 (indicating FALSE) otherwise.
 +
 +==== Greater Than ====
 +
 +We can test is one value is less than another using the > character.
 +
 +===Example===
 +
 +Given two signals TARGET::ORIGINAL::RFT1 and TARGET::ORIGINAL::LFT1, use the Boolean operator > to identify when the Y component of RFT1 is greater than the Y component of LFT1.
 +
 +<code>
 +Evaluate_Expression
 +/EXPRESSION= TARGET::ORIGINAL::RFT1::Y > TARGET::ORIGINAL::LFT1::Y
 +/RESULT_NAME=RFT1_GREATER
 +/RESULT_TYPE=DERIVED
 +/RESULT_FOLDER=PROCESSED
 +;
 +</code>
 +
 +The output signal will be 1 (indicating TRUE) when RFT1::Y is greater than LFT1::Y and 0 (indicating FALSE) otherwise.
 +
 +==== Greater Than Or Equals ====
 +
 +This boolean operator uses one of the following syntaxes: >= or =>.
 +
 +The expression (a >= b) is equivalent logically to ((a > b) | (a == b)).
 +
 +
  
visual3d/documentation/pipeline/expressions/mathematical_operators.1720027697.txt.gz · Last modified: 2024/07/03 17:28 by sgranger