Question

Basically I want shell scripting to run something like this:

time python DoublePendulum.py 1 1 1
time python DoublePendulum.py 1 2 1
time python DoublePendulum.py 1 4 1
time python DoublePendulum.py 1 8 1
time python DoublePendulum.py 1 16 1

(the program produces specially named png files as output)

Answer 1

Assuming that you’ll want to set up some terminating condition for your loop:

increment=1
terminating=2056

while [[ "$increment" -lt "$terminating" ]]
do
    time python DoublePendulum.py 1 "$increment" 1
    increment=$((increment * 2))
done

Explanation:

• increment: The variable that increments itself by multiplying by 2 each time
• terminating: Variable to keep track of when to terminate your loop. (Alternatively, you can do it for how many times you want the loop to run by implementing a separate counter that increments by 1 each time.
• while [[ "$increment" -lt "$terminating" ]]: Run while terminating condition hasn’t been reached.
• time python DoublePendulum.py 1 "$increment" 1: Substitute your increment in.
• increment=$((increment * 2)): Increase your increment.