{"id":12126,"date":"2021-02-19T13:31:58","date_gmt":"2021-02-19T18:31:58","guid":{"rendered":"https:\/\/blogs.mathworks.com\/pick\/?p=12126"},"modified":"2021-02-19T13:31:58","modified_gmt":"2021-02-19T18:31:58","slug":"the-matrix-lab-has-you","status":"publish","type":"post","link":"https:\/\/blogs.mathworks.com\/pick\/2021\/02\/19\/the-matrix-lab-has-you\/","title":{"rendered":"The Matrix Lab Has You"},"content":{"rendered":"
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Sean<\/a>'s pick this week is The Matrix lab has you<\/a> by Mathworlds<\/a>.\r\n <\/p>\r\n <\/introduction>\r\n

I discovered this after reading Brett's post<\/a> a couple weeks ago. It's a fun submission that you guys can run yourself - I won't spoil it. This submission does rely\r\n on some undocumented capabilities that will<\/i> break in the future (some already have). But there will be replacements for those, some already available.\r\n <\/p>\r\n

The thing that caught my eye about this submission was the word of warning on the FEX page: NB : Running this programs clears your Matlab console and may also change some of your Matlab preferences (font and background\r\n colors) if interrupted while running<\/b>.<\/i><\/p>\r\n

The fact that it doesn't reset if interrupted tells me there is improvement for how this function should tear itself down.\r\n Right now it:\r\n <\/p>\r\n

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    \r\n
  1. Gets the original settings values<\/li>\r\n
  2. Sets new settings values<\/li>\r\n
  3. Runs the demo<\/li>\r\n
  4. Sets the settings back to the original value<\/li>\r\n <\/ol>\r\n <\/div>\r\n

    So if you break with ctrl+c or an error occurs, [4] never gets to run. There's a better way to do this using onCleanup<\/tt><\/a> objects. These reliably fire when the object is cleared regardless of if there is an error!\r\n <\/p>\r\n

    I'll demonstrate by changing the command window error color for this MATLAB session using the new documented settings API<\/a>.\r\n <\/p>

    s = settings;\r\ns.matlab.colors.commandwindow.ErrorColor.TemporaryValue = [0 0 255] % blue errors<\/span>\r\ncolorresetter = onCleanup(@()s.matlab.colors.commandwindow.ErrorColor.clearTemporaryValue())<\/pre>
    s = \r\n  SettingsGroup with properties:\r\n                slhistory: [1×1 SettingsGroup]\r\n                 Simulink: [1×1 SettingsGroup]\r\n                   matlab: [1×1 SettingsGroup]\r\ncolorresetter = \r\n  onCleanup with properties:\r\n\r\n    task: @()s.matlab.colors.commandwindow.ErrorColor.clearTemporaryValue()\r\n<\/pre>
    Now when the colorresetter<\/i> variable is cleared, it will automatically clear the value that I'd set.  In a function, this would happen implicitly at\r\n      the end.  So the fact that this error occurs does not mean I'm permanently stuck or need to manually adjust the setting.\r\n   <\/p>
    error('smurf:error'<\/span>, 'This error message is blue'<\/span>)<\/pre>
    Error using mainMatrixLabHasYou (line 52)\r\nThis error message is blue<\/pre>
    I use onCleanup<\/tt> objects all of the time.  Some frequent things I'll use them for:\r\n   <\/p>\r\n   
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