str2num(chr) converts a character array or string scalar to a numeric matrix. The input can include spaces, commas, and semicolons to indicate separate elements. If str2num cannot parse the input as numeric values, then it returns an empty matrix. The str2num function does not convert cell arrays or nonscalar string arrays, and is sensitive to spacing around + and - operators. str2num() contains a call to eval(), which means that if your string has the same form as an array (e.g. with semicolons) then it is simply executed and the resulting array is returned. The problems with str2num() are that it doesn’t support cell arrays, and that because it uses an eval() function, wierd things can happen if your string includes a function call. str2double() is supposedly faster as well. So the general rule seems to be, use str2double() unless you are wanting to convert a string array of numbers to a numerical array. There is one catch though- if you are converting a single number from a string to a number, then it would SEEM like str2num() and str2double() are interchangable, drop in replacements. However, if the string is not a number, they behave differently

str2double will only convert text that represents real or complex scalar values. Where y is a char array of binary values. It is basically interpreting y as one large integer. Hence, it will return NaN or Inf depending on the version of MATLAB you are using.

The fastest conversion uses low-level commands, e.g. sprintf and sscanf. Instead of this: C = {'1.2','3.4','5.6'}; V = str2double(C) do this (add reshape if required, or specify the optional size argument): V = sscanf(sprintf(' %s',C{:}),'%f',[1,Inf]) See also: https://undocumentedmatlab.com/articles/some-performance-tuning-tips

https://www.mathworks.com/matlabcentral/answers/437449-matlab-coder-giving-issue-with-textscan#answer_354189 X = "3.716,3.711,3.719,3.714,3.714,3.711,3.722,3.712,3.715,3.715,3.717,3.721,3.713,3.714,0.000"; str = X{1}; % character vector idx = str==','; idy = diff([true,idx,true]); idb = find(idy<0); ide = find(idy>0)-1; num = numel(idb); tmp = cell(num,1); for k = 1:num tmp{k} = str(idb(k):ide(k)); end vec = str2double(tmp)

The reason for the observed behavior is the stdio library used by Arduino. The code generated by str2double uses a function called sscanf. This function internally calls vfscanf function. vfscanf is available in three different versions. Out of these three versions, the default version does not implement scanning float variables. This is mentioned in the doc: "By default, all the conversions described above are available except the floating-point conversions and the width is limited to 255 characters. The float-point conversion will be available in the extended version provided by the library libscanf_flt.a. Also, in this case the width is not limited (exactly, it is limited to 65535 characters). To link a program against the extended version, use the following compiler flags in the link stage: -Wl,-u,vfscanf -lscanf_flt -lm " Refer the following doc link for more details: https://www.nongnu.org/avr-libc/user-manual/group__avr__stdio.html#ga67bae1ad3af79809fd770be392f90e21 To use compiler flags mentioned in the doc, you can follow the steps mentioned below: 1. Open config set 2. Go to "Code Generation" tab 3. In "Build configuration" drop down, select "Specify" 4. In C++ Liker, append the following: -Wl,-u,vfscanf -lscanf_flt -lm 5. Dont forget to add a space to the existing flags before appending the new flags. 6. Click apply, OK. 7. Run the model in external mode. Please note that using the extended version of this library will consume a lot of code space.

Gil - is each element of your cell array a numeric scalar or numeric array? See which provides some examples on how you might do this conversion.