Ventana software support forum

Hi,

My model has 73249 time steps and when I run it, I get this error at different time steps:
"Not enough memory-decrease lenght or increase SAVEPER"

As it occures at different time steps I would like to ask you what is your suggestion for fixing it.

Best Regards,

How big is the model? (You can find the equation counts on the Model>Settings>Info tab.)

One option would be to switch to the 64-bit version.

tomfid wrote: ↑Sat Jan 05, 2019 6:54 pm How big is the model? (You can find the equation counts on the Model>Settings>Info tab.)

One option would be to switch to the 64-bit version.

Attached please find my model info.

Wow - this is huge to run with such a fine time step - it's generating something like 200 billion floating point numbers. I think you probably need 64-bit, even with other strategies like using a savelist to reduce storage.

What is this about?

tomfid wrote: ↑Sun Jan 06, 2019 4:37 pm Wow - this is huge to run with such a fine time step - it's generating something like 200 billion floating point numbers. I think you probably need 64-bit, even with other strategies like using a savelist to reduce storage.

What is this about?

I am using a savelist with 100 variables in its list. Does number of variables in savelist affect it? The model simulates electricty market of Europe.

tomfid wrote: ↑Sun Jan 06, 2019 4:37 pm Wow - this is huge to run with such a fine time step - it's generating something like 200 billion floating point numbers. I think you probably need 64-bit, even with other strategies like using a savelist to reduce storage.

What is this about?

I have increased size of the model by adding more powerplants to it and it takes 17 hours for simulations( I am simulating electricity market for 35 years). Is it true that some of functions might not be supported by 64bit version? If yes, can I ask you which functions? And do you have any estimation how much new 64bit version can decrease running time?

64 bit Vensim will have all the same functions as 32 bit Vensim. If you use external functions, you will need to re-compile these to create a 64 bit DLL before use.

64 bit version will not decrease running time (it will probably take longer to run).

Administrator wrote: ↑Wed Feb 27, 2019 10:59 am 64 bit Vensim will have all the same functions as 32 bit Vensim. If you use external functions, you will need to re-compile these to create a 64 bit DLL before use.

64 bit version will not decrease running time (it will probably take longer to run).

Do have any other suggestion for decreasing running time?

Are you compiling the model?

There are other things you can do to optimize the model. For example, if you are calculating a proportion, a lot of users will do something like

proportion[country] = sales[country] / sum ( sales[country!] )

If you have 100 countries, the "sum ( sales[country!])" is calculated 100 times (once for every country). If you do the following,

total sales = sum ( sales[country!] )
proportion[country] = sales[country] / total sales

"sum ( sales[country!] )" is only calculated once. This can really improve model performance. The same goes for any vector functions that appear on the right hand side of an equation.

https://metasd.com/2011/01/optimizing-vensim-models/ has some tips.