Teledyne LeCroy WaveExpert 100H Operators Manual - Manual (Page 278)

Operator’s Manual
276
WE-OM-E Rev A
Notes:
If there is any possibility that you will be taking the exponent of a negative number, make sure to trap any possible errors
arising from such operations as trying to take the square root of a negative number. Logs of negative numbers are forbidden
also.
If there is any possibility that you will be dividing by zero, make sure to trap this.
There are two ways of dealing with these types of problem. One is to prevent it happening by making suitable tests before
the calculation is performed. The other is to let it happen, and use an error handling routine. This will be discussed later.
Normally in VBScript you will know the range of the data, since all the incoming data are, by definition, integer (unscaled
data) or real (scaled data), and they must fit into the screen of the instrument.
Results of Calculations
Sometimes you may see a statement like this:
A = A * A * (Cos (A) + Sin (A) )
The program takes the quantity represented by A and performs all of the following operations, using
that original value:
1. Multiply A by itself.
2. Calculate the cosine of A.
3. Calculate the sine of A.
4. Add the cosine and the sine together.
5. Multiply that result by the square of A.
At this point, the quantity represented by A has not been changed. Only at the end of the calculation
is the final value placed in the memory location labeled A.
Note that you can write more than one statement on a line, separated by colons, like this
A = B * Cos (34 * Theta) * Sin (55 * Theta) : B = A * A + Z * Z
Order of Calculations
Operations are performed in the following order:
1. Contents of brackets.
2. Exponentiation.
3. Division and multiplication.
4. Addition and subtraction.
If there is any doubt as to how the calculation will be done, use brackets. These will also make the
order of the calculations clear to any reader of the program, which is desirable if you are to give it to
a customer, who will want to know what was intended.