Programming in LabVIEW MathScript-For Loops

The For Loop

The for loop is one way to make LABVIEW MATHSCRIPT repeat a series of computations using different values. The for loop has the following syntax:

 for d = array     % LABVIEW MATHSCRIPT command 1     % LABVIEW MATHSCRIPT command 2     % and so on end 

In the for loop, array can be any vector or array of values. The for loop works like this: d is set to the first value in array, and the sequence of LABVIEW MATHSCRIPT commands in the body of the for loop is executed with this value of d. Then d is set to the second value in array, and the sequence of LABVIEW MATHSCRIPT commands in the body of the for loop is executed with this value of d. This process continues through all of the values in array. So a for loop that performs computations for values of d from 1.0 to 2.0 is:

 for d = 1.0:0.05:2.0     % LABVIEW MATHSCRIPT command 1     % LABVIEW MATHSCRIPT command 2     % and so on end 

(Recall that 1.0:0.05:2.0 creates a vector of values from 1.0 to 2.0.)

Note that in all of the examples in this module, the LABVIEW MATHSCRIPT commands inside the for loop are indented relative to the for and end statements. This is not required by LABVIEW MATHSCRIPT but is common practice and makes the code much more readable.

A useful type of for loop is one that steps a counter variable from 1 to some upper value:

 for j = 1:10     % LABVIEW MATHSCRIPT commands end 

For example, this type of loop can be used to compute a sequence of values that are stored in the elements of a vector. An example of this type of loop is

 % Store the results of this loop computation in the vector v for j = 1:10     % LABVIEW MATHSCRIPT commands     % More LABVIEW MATHSCRIPT commands to compute a complicated result     v(j) = result; end 

Using a for loop to access and manipulate elements of a vector (as in this example) may be the most natural approach, particularly when one has previous experience with other programming languages such as C or Java. However, many problems can be solved without for loops by using LABVIEW MATHSCRIPT's built-in vector capabilities. Using these capabilities almost always improves computational speed and reduces the size of the program. Some would also claim that it is more elegant.

For loops can also contain other for loops. For example, the following code performs the LABVIEW MATHSCRIPT commands for each combination of d and c:

 for d=1:0.05:2     for c=5:0.1:6         % LABVIEW MATHSCRIPT Commands     end end