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14-4 Variables and Substitution

Global Variables
May be used as variables within parameters, point coordinates, table cells, and scripts.

Local Variables
Four local variables (x, y, z, w) may be used. These variables are valid only within a script during
execution. For example, variable x in script A and variable x in script B are unrelated.
Real numbers and error values may be substituted in local variables. Use X and Y when handling
two-dimensional vector values with local variables. X is a variable set (x, y) and may therefore be written
X = (x, y). Similarly, Y = (z, w).
Example: X = (1, 2)
and
x := 1
y := 2
return the same result.
The initial value of a local variable is an error value which is discarded after execution. When a script is
called with the CALL command during execution of another script, the argument for the CALL statement
is substituted in these variables.
Example: If the following is written in a C language-like format,
//Sum
a := x+y
it appears as follows.
void Sum( x , y , z , w);
{a=x+y}

Substitution
Equation values may be substituted in parameters, point coordinates, table cells, and local variables x, y,
z, and w as follows.
Substitution object ;= equation
Leave a space between the substitution object and „:=‟.the same applies between „:=‟ and the equation.
If the equation has no value (e.g. 1/0) when substituting in parameters and points (coordinate
component), the substitution statement is not executed.

Parameter := equation
Example: a := sin t
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