Using App Designer, reading a numeric edit field and creating a double array from the inputs?

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Scotty Mac
Scotty Mac 2023-4-22
评论： Stephen23 2023-4-23
I have 3 NumericEditFields and I enter 5700 & 4750 in the first 2 (the 3rd can be blank and thus only have an array with only 2 elements). I then convert them from MegaHertz to Hertz by the following:
if isempty(app.NumericEditField_NotchCenterFreq1.Value) % check to see if the field is empty first, if so, assign an empty string
fc1 = {};
else
fc1 = app.NumericEditField_NotchCenterFreq1.Value;
fc1 = fc1 * 10e6; % Convert to Hertz
end
if isempty(app.NumericEditField_NotchCenterFreq2.Value)
fc2 = {};
else
fc2 = app.NumericEditField_NotchCenterFreq2.Value;
fc2 = fc2 * 10e6; % Convert to Hertz
end
if isempty(app.NumericEditField_NotchCenterFreq3.Value)
fc3 = {};
else
fc3 = app.NumericEditField_NotchCenterFreq3.Value;
fc3 = fc3 * 10e6; % Convert to Hertz
end
% Create an array from entered inputs
notch_fc=[fc1, fc2, fc3];
make_loadset(app, notch_fc);
The notch_fc array is
notch_fc: 1×2 cell array =
[1×4 double] [1×4 double]
But I want it to be a double array (values for example)
notch_fc: 1x2 double =
1.0e+09 *
5.7000 4.7500
How can I accomplish this? I have searched and searched and can not find the answer. Thanks in advance!

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Stephen23
Stephen23 2023-4-22
编辑：Stephen23 2023-4-22
Ran in:
The reason why it is a cell array is because you told MATLAB to make a cell array. Basically you are doing this:
fc1 = 1;
fc2 = pi;
fc3 = {}; % if this is a cell array...
[fc1,fc2,fc3] % then so is this.
ans = 1×2 cell array
{[1]} {[3.1416]}
If any input to the concatenation operator is a cell array, then the output will be a cell array. This is explained here:
https://www.mathworks.com/help/matlab/matlab_prog/combining-cell-arrays-with-non-cell-arrays.html
https://www.mathworks.com/help/matlab/matlab_prog/valid-combinations-of-unlike-classes.html
Ergo, if you do not want a cell array output, do not provide cell arrays as the inputs.
"How can I accomplish this? I have searched and searched and can not find the answer."
If you want a numeric vector output then you need to provide numeric inputs. Note that numeric arrays cannot have "holes" in them, i.e. every element must contain some value. Some solutions:
  • output may change size: use empty numeric [].
  • output must remain same size: use NaN.
Lets try them both, right now:
fc3 = NaN; % numeric NaN
[fc1,fc2,fc3]
ans = 1×3
1.0000 3.1416 NaN
or
fc3 = []; % numeric empty
[fc1,fc2,fc3]
ans = 1×2
1.0000 3.1416

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