~ means NOT so *isempty* tells you if the vector is empty and *~isempty* tells you if the vector is _not_ empty. Answer from Adam on mathworks.com
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MathWorks
mathworks.com › matlabcentral › answers › 378004-why-is-an-empty-string-not-empty-isempty-returns-true-but-isempty-returns-false
Why is an empty string not empty? isempty('') returns true, but isempty("") returns false - MATLAB Answers - MATLAB Central
January 19, 2018 - Strings, added in R2016b, are a great addition to matlab, but one aspect is a problem: testing for empty variables with isempty() no longer gives a consistent response. ... One would expect that if the two values are considered equal, that a builtin function like isempty() would produce the same result. Presumably "" is not empty because it is a string object, while '' really is the same as [ ]. But this is a problem for code that tests for empty character input using isempty(...).
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MathWorks
mathworks.com › matlab › software development tools › testing frameworks › write unit tests
matlab.unittest.constraints.IsEmpty - Test if value is empty - MATLAB
The test fails because the cell array is not empty. ... Verification failed. --------------------- Framework Diagnostic: --------------------- IsEmpty failed. --> The value must be empty. --> The value has a size of [1 3]. Actual Value: 1×3 cell array {0×0 double} {0×0 double} {0×0 double} Test an empty test suite. The test passes. ... Verification passed. ... matlab.unittest.constraints.HasElementCount | matlab.unittest.constraints.HasLength | matlab.unittest.constraints.HasSize | matlab.unittest.constraints.IsScalar | verifyEmpty | verifyThat | isempty
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MathWorks
mathworks.com › matlab › programming › classes › define classes › properties
mustBeNonempty - Validate that value is nonempty - MATLAB
Error setting 'Prop1' property of 'MyClass' class. Value must not be empty. When you assign a value to the property, MATLAB calls mustBeNonempty with the value being assigned to the property.
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MathWorks
mathworks.com › system identification toolbox
isempty - Determine whether dynamic system model is empty - MATLAB
The isempty command returns 1 because the system does not have any outputs. Similarly, isempty returns 1 for an empty transfer function. ... Now create a state-space model with 1 input and 1 output. In this example, specify the A, B, C, and D matrices as 1, 2, 3, and 4, respectively. ... Determine whether sys2 is empty. ... The command returns 0 because the system has inputs and outputs. ... Run the command by entering it in the MATLAB Command Window.
Find elsewhere
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MathWorks
mathworks.com › matlab › language fundamentals › data types › characters and strings
Test for Empty Strings and Missing Values - MATLAB & Simulink
Do not use the isempty function to test for empty strings. A string with zero characters still has a size of 1-by-1.
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Northwestern University
ece.northwestern.edu › local-apps › matlabhelp › techdoc › ref › isempty.html
isempty (MATLAB Functions)
isempty · Test if array is empty · Syntax · tf = isempty(A) · Description · tf = isempty(A) returns logical true (1) if A is an empty array and logical false (0) otherwise. An empty array has at least one dimension of size zero, for example, 0-by-0 or 0-by-5 · Examples · B = rand(2,2,2); ...
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MathWorks
mathworks.com › matlabcentral › answers › 797582-isempty-function-does-not-work-for-me
isempty function does not work for me - MATLAB Answers - MATLAB Central
April 9, 2021 - Sometimes I get an emtpy array and Sometimes I do not, However, when I use the "isempty" function it tells me that it's not empty even when it is. Since "out1" is empty shouldnt the logical output be 1 and not 0? any help is greatly appreciated. Thank you ... https://www.mathworks.com/matlabcentral/answers/797582-isempty-function-does-not-work-for-me#comment_1450182
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Quora
quora.com › How-do-you-check-if-a-variable-is-empty-in-MATLAB
How to check if a variable is empty in MATLAB - Quora
Answer: [code]>> doc isempty [/code]Note the distinction in MATLAB between a variable that exists, but has no meaningful value (apart from the null matrix), and a variable that doesn’t exist at all: [code]>> doc exist >> doc clear >> doc clearvars [/code]An empty variable is often a useful signa...
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MathWorks
mathworks.com › matlab › language fundamentals › matrices and arrays
isempty - Determine whether array is empty - MATLAB
TF = isempty(A) returns logical 1 (true) if A is empty, and logical 0 (false) otherwise. An empty array, table, or timetable has at least one dimension with length 0, such as 0-by-0 or 0-by-5. ... Create a 3-D array with one dimension length equal to zero, and determine if it is empty.
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Reddit
reddit.com › r/matlab › why does isempty return false?
r/matlab on Reddit: Why does isempty return false?
September 1, 2015 -

I am fairly new to MatLab and am using it to inspect an array of strings to determine whether each element contains a string (specifically, the letter 'a'). When prompting isempty(strfind(TEST(1), 'a')), where TEST(1) does not contain an 'a', it returns FALSE (i.e. 0).

strfind(TEST(1), 'a') returns {[]}

Any help resolving this issue and possibly helping me understand why the result is not TRUE (i.e. 1)?

Edit: Wow thank-you for all of the thorough responses. I'll get back to working on my project tomorrow at work. This looks to be a very supportive community - although the submitted posts seem to get downvoted a lot.

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Linux Hint
linuxhint.com › isempty-function-matlab
The isempty Function in MATLAB
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