Execution time is varying every time I run the program using tic toc. Is there any way to solve this?

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Palguna Gopireddy 2022-8-12

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评论： Palguna Gopireddy 2022-8-25

I am running a code. The execution time of it is varying. If it of the order of milli seconds I understand it. But it is varying of the order of decades of milliseconds.

Like sometimes it is showing (in seconds).

0.189348

0.186602

0.110847

0.205987

22.769279

I am using matlab 2021a with all other apps closed.

Each time I am clearing the workspace and closing and opening the desktop app also. I want to know the correct way to find the execution time. How can do it.

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Jan 2022-8-12

编辑：Jan 2022-8-13

See: doc clear

Use e.g. clear variables or clear with the specific names of variables your want to delete.

clear is rarely useful in Matlab and used too often without a good reason. You do not have to clear a variable to calculate it again.

Palguna Gopireddy 2022-8-12

Thanks @Bjorn Gustavsson, @Jan, @dpb.

As @Bjorn Gustavsson suggested, I used timeit function and loaded the data from external disc seperately and passed it to the function.

The time is only varying of the order of milli secconds only.

I think its good result.

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回答（1 个）

Shivani Dixit 2022-8-25

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Hello,

As per the data provided it seems the tic and toc functions display approximately same values except for times when values exceed the order of 10.

The tic and toc functions returned incorrect results because:

The standard processor driver presented the wrong information to the Windows QueryPerformance interface about which timer to use.
In those cases where the CPU independent APIC clock should have been used, the CPU cycle counter was used instead. The CPU cycle counter can be used only if the processor speed does not vary and if all the cores in the multi-core case appear to be synchronized.

As a solution to this issue, I would like to suggest to:

Install the patch for your hardware starting with the corresponding URL shown below. Reboot your system and rerun the required MATLAB file. It should now pass.

1. Athlon processors

http://www.amd.com/us-en/Processors/TechnicalResources/0,,30_182_871_9706,00.html

   There is one patch that can be applied for both Windows XP and
   Windows XP64.  Look for a title that begins:
   ----------------------------------
   AMD Athlon 64/FX Processor Driver for Windows XP and
   Windows Server 2003 Version (x86 and x64 exe)
   ----------------------------------
   The version and date will change for time. The latest should always work.

2. Opteron processors

http://www.amd.com/us-en/Processors/TechnicalResources/0,,30_182_871_9033,00.html

   There is one patch that can be applied for both Windows XP and
   Windows XP64.  Look for a title that begins:
   ----------------------------------
   MD Opteron Processor with AMD PowerNow Technology Driver
   for Windows XP and Windows Server 2003 Version
   (x86 and x64 exe)
   ----------------------------------
   The version and date will change for time. The latest should always work.