IF
You can use the arithmetic IF operator to conditionally evaluate a functional expression.
IF (expression 1: expression 2, expression 3, expression 4)
The method evaluates expression 1, and then operates as follows:
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If the value of expression 1 is less than zero, the arithmetic IF is evaluated using expression 2.
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If the value of expression 1 is equal to zero, the arithmetic IF is evaluated using expression 3.
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If the value of expression 1 is greater than zero, the arithmetic IF is evaluated using expression 4.
Format
IF (A: X, Y, Z)
Arguments
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A
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Any valid function expression. The software evaluates the expression to determine which branch of the arithmetic IF <X, Y, Z> is selected.
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X
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Any valid function expression. If the value of the test expression is less than zero, the software evaluates the X expression and the IF function takes on the value of X. Otherwise, the X expression is not evaluated.
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Y
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Any valid function expression. If the value of the test expression is equal to zero, the software evaluates the Y expression and the IF function takes on the value of Y. Otherwise, the Y expression is not evaluated.
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Z
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Any valid function expression. If the value of the test expression is greater than zero, the software evaluates the Z expression and the IF function takes on the value of Z. Otherwise, the Z expression is not evaluated.
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Cautions
When using an arithmetic IF function to define motion, make sure that the resulting motion or force is continuous. If the motion or force is discontinuous, the motion simulation may fail to find a solution. It is best if all functions you use to define motion or forces have continuous first and second derivatives. It is best if you do not use the if function to define motion.