MTS Multipurpose Elite - Manual (Page 213)

Description Item Number
Note:
The variable parameters between the parentheses are
not the identities of the variables. They indicate the type
of variable that must be placed in the syntax.
For More Information
Concept
Calculation Unit Conversion Issues (p. 213)
Notation for Referencing Variables (p. 214)
Task
Calculation Unit Conversion Issues
Important:
To avoid unit-conversion issues, create a variable to hold any constant value (that has a dimension
and units associated with it) used in a calculation. You can assign any units that you want to the
variable and the application converts them to the base units when the calculation is performed.
Base units
Although MTS TestSuite applications allow the user to specify variable units, all calculations convert
variable values and constants to a constant set of base units. This can be problematic if you add a constant
to an equation and assume that it will use the same user-assigned units as the other variables in the
calculation.
Note:
When using the Calculation Editor, you can move the mouse over any variable in the calculation to
display a tool tip that specifies the base units used when that calculation is performed.
Example
For example, the following calculation would yield incorrect results because the test designer has entered
a constant that they assumed would match the user-assigned units.
y = x +(1)
where: the variable (x) has user-assigned units of feet and the constant (1) is assumed to also have the
same units of feet.
If the value of x=3 feet the assumption is that:
y = 3 ft. + 1 ft. = 4 ft. where: y is a variable with a dimension = “length” and units = feet
But, because the constant (1) is converted to the application’s base units for length (meters in this example),
the equation returns the following:
y = 0.9144 + 1 = 1.9144 so that: the displayed value of y = 6.281 ft. (not 4 ft.)
For More Information
MTS TestSuite | 213
Working with Variables