Stata 15 help for stataic

Using Stata/IC

There are three flavors of Stata:

Flavor Description ----------------------------------------------- -> Stata/IC standard version Stata/SE Stata/IC + large datasets Stata/MP Stata/SE + parallel processing ----------------------------------------------- See [U] 5 Flavors of Stata for descriptions

To determine which flavor of Stata you are running, type

. about

If you are using a different flavor of Stata, click on the appropriate link:

----------------------------------------------- Stata/SE Using Stata/SE Stata/MP Using Stata/MP -----------------------------------------------

For information on upgrading to Stata/SE or Stata/MP, point your browser to http://www.stata.com.

Contents

1. Starting Stata/IC

2. Setting Stata/IC's limits 2.1 Advice on setting matsize

3. Sharing .dta datasets with non-IC users

4. Querying memory usage

5. Advice to programmers: Determining flavor

1. Starting Stata/IC

You start Stata/IC as follows:

Windows: Select Start > All Programs > Stata 15.1 > StataIC 15.1

Mac: Double-click the file Stata.do from the data folder, or double-click the Stata icon from the Stata folder.

Unix: At the Unix command prompt, type xstata to invoke the GUI version of Stata/IC, or type stata to invoke the console version.

2. Setting Stata/IC's limits

The two limits for Stata/IC are as follows:

1. maxvar The maximum number of variables allowed in a dataset. This limit is set to 2,048 and cannot be reset.

2. matsize The maximum size of matrices, or said differently, the maximum number of independent variables allowed in the models that you fit. This limit is initially set to 400, and you can increase it up to 800.

You set the limit by using the

set matsize # [, permanently]

command. For instance, you might type

. set matsize 500

If you specify the permanently option when you set a limit, in addition to making the change for the present session, Stata/IC will remember the new limit and use it in the future when you invoke Stata/IC:

. set matsize 500, permanently

You can reset the present or permanent limit whenever and as often as you wish.

2.1 Advice on setting matsize

set matsize # [, permanently] 10 <= # <= 800

The name matsize is unfortunate because it suggests something that is only partially true. It suggests that the maximum size of matrices is matsize x matsize. matsize, however, is irrelevant for the size of matrices in Mata, Stata's modern matrix-programming language. Regardless of the value of matsize, Mata matrices be larger or smaller than that.

matsize specifies the maximum size of matrices in Stata's old matrix language -- and that is not of great importance -- and it specifies the maximum number of variables that may appear in Stata's estimation commands -- and that is important. A better name for matsize would be modelsize.

With that introduction, let us begin.

The value of matsize has a dramatic effect on memory usage, the formula being

Number of megabytes = (8*matsize^2 + 88*matsize)/(1024^2)

For instance,

+--------------------------+ | matsize | memory use | |-----------+--------------| | 40 | .015M | | 100 | .084M | | 200 | .322M | | 400 | 1.254M | | 800 | 4.950M | +--------------------------+

The formula, in fact, understates the amount of memory certain Stata commands use and understates what you will use yourself if you use Stata's old matrix language matrices directly. The formula gives the amount of memory required for one matrix and 11 vectors. If two matrices are required, the numbers above are nearly doubled.

Choose a reasonable value given the kinds of models you fit.

3. Sharing .dta datasets with non-IC users

You may share datasets with Stata/SE and Stata/MP users with no changes necessary.

4. Querying memory usage

The command

. memory

will display the current memory report and the command

. query memory

will display the current memory settings. See help memory.

5. Advice to programmers: Determining flavor

Programmers can determine which flavor of Stata is running by examining the creturn values

creturn values | c(flavor) c(SE) c(MP) ------------+------------------------------ Stata/IC | "IC" 0 0 Stata/SE | "IC" 1 0 Stata/MP | "IC" 1 1 -------------------------------------------


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