Thread: lookup tables storage location

Hi folks. I am solving some equations and then storing the solutions in a lookup table that also serves as an interpolation table. My questions are: 1) Where is the lookup table stored? (The reason I don't know where the table is stored is because I use the maths package gsl and don't know enough programming myself.)

2) If I make the lookup table in a c file and then use it in a couple of other c files and only de allocate the memory after the program is about to end, will it make my code slow?

Instead of copying the entire code here, I am pasting this link to the gsl example.

The general format seems to be
1) allocate memory 2) use the lookup table for your caculations 3) de allocate the memory. But my problem is that I do the step 2) i.e use the lookup table in other c files. My code would do something like this

in file one 1) allocate memory 2) create a lookup table
in file two 3) use the lookup table in various calculations repeatedly
from which file, one or two should I de allocate the memory? or it does not matter as long as it is done. Here is the link

Interpolation Example programs - GNU Scientific Library -- Reference Manual

Can you please also tell me topics I need to read about that are related to what I am trying to do here. I have some idea that I should read malloc and dynamic memory allocation. I am still a couple of chapters behind in the book, will get there soon. Do I need to know how to store data to cache?

thank you for responding. I am bad at making myself clear. I was worried about that if the lookup table is stored in RAM then that would be a waste of memory. Wouldn't it be a better thing if instead the table were saved in say a .dat file and read from when required. How do the guys who know what they are doing it do it? And the other thing is that I would have about 10 different lookup tables. I guess it is easily handled by c, just have to create a struct with all the lookup tables as its members.

How much RAM you mind using depends on the circumstances.

Unless the table is well into the hundreds of Mb or you are running very limited hardware it's fine to use RAM for this. Probably quite a few of the things running on your desktop right now are anyway, right?

If this a process that is going to run continuously in the background, you probably want to be more polite and conservative with resources. However, "resources" includes CPU usage and disk access, which I think that's what you will end up consuming by "saving RAM" in this case, and IMO -- again, unless this is a really huge table -- that tradeoff will not be worth it. So use RAM.

If instead it is something intended to exploit the power of the processor as much as possible -- ie, you want your calculations done ASAP, even if that completely occupies the computer for whatever time period -- definitely use RAM up to the point where there is none left to use, then swap to disk.