numlabs

(Not recommended) Number of workers running current spmd block

numlabs is not recommended. Use spmdSize instead. For more information, see Version History.

Syntax

n = numlabs

Description

n = numlabs returns the number of workers running the current spmd block or communicating job. This value is the maximum value that can be used with labSend and labReceive.

Examples

Find Number of Workers in spmd Block

This example shows how to run numlabs inside and outside an spmd block.

Create a parallel pool with 4 workers.

parpool(4);

When you execute an spmd block after creating a parallel pool, by default all available workers in the pool will run the code inside the spmd block.

Run numlabs inside and outside an spmd block. In the block, the returned value is equal to the number of workers. Outside the block, the returned value is 1.

spmd
    disp(numlabs)
end
disp(numlabs)

Worker 1: 
       4
  
Worker 2: 
       4
  
Worker 3: 
       4
  
Worker 4: 
       4
  
     1

Output Arguments

n — Number of workers

positive integer scalar

Number of workers running the current spmd block or communicating job, specified as an integer. In an spmd block, numlabs returns the number of workers running the spmd block. Outside an spmd block, numlabs is 1.

When you create a communicating job using createCommunicatingJob, you can run a function or script on N workers. When one of the workers runs numlabs, the returned value is N.

Version History

Introduced before R2006a

R2022b: numlabs is not recommended

To indicate their intended use within spmd blocks, numlabs is renamed to spmdSize. numlabs will continue to work but is no longer recommended. To update your code, replace any instance of numlabs with spmdSize. There are no plans to remove numlabs.