Transcript The Script Element

GoldSim Monthly Webinar Series
Goals
Learn the basics of simple scripts
 Learn the basics of the GoldSim Script
Element
 Not a lesson on numerical methods

What is a Script?
A set of instructions
 Carried out by another program
 Instructions are executed and
something(s) is (usually) returned as
output
 Script languages are easier and faster to
code in

Why use the Scripts?

Clarify complex logic
 Nested IF statements
 Iterate through items of an array

Condense equations
 Repetitive equations
 Long series of equations

Numerical solution required
 Iterative solvers like bisection
Different Ways in GoldSim
GoldSim elements, looping containers
 Equations in Excel produce output that
is read by GoldSim
 External functions connected to
GoldSim

 DLL Element

Write a script inside GoldSim
 Script Element
Advantages of the Script
All in one program
 Transparent
 No need to learn a new language

Main Functions
Variable definition
 Variable assignment
 Flow control (i.e. IF, looping, break)
 Comments
 Log Statements

Variable Definition

Syntax:
 Define: peak_price = 0.0 $/m3

Declaration:
 Number (float: double precision) or Boolean
 scalar or non-scalar
Initialize to a value
 Description
 Expose as Output

Variable Assignment

Syntax:
 ~peak_price = 50 $/m3
 Result = ~peak_price

Local vs. Global variables
For Loop
Loop Variable, Start Value, Loop while
Condition, Increment by
 Syntax:

FOR (i = 0; ~i < 10; i = ~i + 1)
{do some work}
END FOR
DO Loop
Loop Variable, Start Value, End Value,
Increment by
 Syntax:

DO i = 0, 10, 1
{do some work}
END DO
REPEAT-UNTIL Loop
Loop until true: Some Condition
 Syntax:

REPEAT
{do some work}
UNTIL (~price > 30 $/m3)
WHILE Loop
Loop while true: Some Condition
 Syntax:

WHILE (~price < 10 $/m3)
{do some work}
END WHILE
BREAK and CONTINUE

Only allowed inside Loop structures

BREAK
 Break out of a loop
 Breaks the nearest enclosing loop

CONTINUE
 Transfer control to the bottom of the loop
 Used to skip to the next loop without
executing block in the loop
Comments
Document the operation of the program
 Intended for others and yourself
 Max 100 characters
 Ctrl-Enter extra lines only seen in
printout
 White space

Log Statements

Message
 Message to Run Log
 No warning

Warning
 Message
 Warning dialogue message

Error
 Message
 Simulation is stopped with dialogue
message
Prioritize Days By Price
Save days as numbers in a vector in order of
greatest unit price to lowest. Only show values
that meet criteria.
Peak Price Days
8
2
1
7
9
Formulation
Save all values to an array of days
 Loop thru the list (array)
 If the max(list) is <= $0/m3, then done!
 Stuff the day of max price to temp
variable
 Assign temp to Result Array at current
index
 Remove the current max price from list
 Loop

Create Table of Best Days
Day
1
2
3
4
5
6
7
8
9
10
price
0.84147
0.9093
0.14112
-0.7568
-0.95892
-0.27942
0.65699
0.98936
0.41212
-0.54402
1
2
3
4
5
6
7
8
9
10
Best days
8
2
1
7
9
3
Final Result