Maximizing MATLAB Performance (Programming and Data Types)

Programming and Data Types

Viewing profile Results

There are two main ways to view profile results:

To save results, see Saving Profile Reports.

Viewing profile Reports. To display profile results, type

```
profile report
```

This suspends profile and produces three reports:

The summary report appears in your system's default Web browser. Use the links at the top of the report page to see the other reports.

Summary profile Report. The summary report presents statistics about the overall execution and provides summary statistics for each function called. Values reported include

Number of functions--The numbers of built-in functions, M-functions, and M-subfunctions are reported.
Clock precision--The precision of profile time measurement. When Time for a function is 0, it is actually a positive value, but smaller than profile can detect given the clock precision.
Time columns--The total time spent in a function, including all child functions called. Because the time for a function includes time spent on child functions, the times do not add up to the Total recorded time and the percentages add up to more than 100%.
Self time columns --The total time spent in a function, not including time for any child functions called. Adding the Self time values for all functions listed equals the Total recorded time. The Self time percentages for all functions add up to approximately 100%.

Note that profile itself uses some time, which is included in the results.

Following is the summary report for the Lotka-Volterra model described in An Example Using profile.

Function Details profile Report. The function details report provides statistics for the parent and child functions of a function, and reports the line numbers on which the most time was spent. Following is the detail report for the lotka function, which is one of the functions called in An Example Using profile.

Function Call History Profile Report. The function call history displays the exact sequence of functions called. To view this report, you must have started profile using the -history option.

```
profile on -history
```

The profile function records up to 10,000 function entry and exit events. For more than 10,000 events, profile continues to record other profile statistics, but not the sequence of calls. Following is the history report generated from An Example Using profile.

Profile Plot. To view a bar graph for the functions using the most execution time, type

```
profile plot
```

This suspends the profile. The bar graph appears in a figure window. Following is the bar graph generated from An Example Using profile.

Saving Profile Reports. When you generate the profile report, use the basename option to save it. For example,

```
profile report basename
```

saves the profile report to the file basename in the current directory. Later you can view the saved results using a Web browser.

Another way to save results is with the info = profile function, which displays a structure containing profile results. Save this structure so that later you can generate and view the profile report using profreport(info).

Example Using Structure of Profiler Results. The profile results are stored in a structure that you can view or access. This example illustrates how you can view the results:

Run profile for code that computes the Lotka-Volterra predator-prey population model.

profile on -detail builtin -history
[t,y] = ode23('lotka',[0 2],[20;20]);

To view the structure containing profile results, type

```
stats = profile('info')
```

MATLAB returns

stats = 
      FunctionTable: [41x1 struct]
    FunctionHistory: [2x826 double]
     ClockPrecision: 0.0100
               Name: 'MATLAB'

You can view and access the contents of the structure. For example, type

```
stats.FunctionTable
```

MATLAB displays the FunctionTable structure.

ans = 
41x1 struct array with fields:
    FunctionName
    FileName
    Type
    NumCalls
    TotalTime
    TotalRecursiveTime
    Children
    Parents
    ExecutedLines

To view the contents of an element in the FunctionTable structure, type, for example:

```
stats.FunctionTable(2)
```

MATLAB returns the second element in the structure.

ans = 
          FunctionName: 'horzcat'
              FileName: ''
                  Type: 'Builtin-function'
              NumCalls: 43
             TotalTime: 0.0100
    TotalRecursiveTime: 0.0100
              Children: [0x1 struct]
               Parents: [2x1 struct]
         ExecutedLines: [0x3 double]

Save the results:

```
save profstats
```

In a later session, to generate the profile report using the saved results, type

```
load profstats
profreport(stats)
```

MATLAB displays the profile report.

An Example Using profile Making Efficient Use of Memory