How to change number precision with writestruct

The number of significant digits of writestruct is quite limited, as showed by this example

s=struct('pi',pi);
writestruct(s,'pi.xml');
type pi.xml

<?xml version="1.0" encoding="UTF-8"?>
<struct>
    <pi>3.1416</pi>
</struct>

Does anyone know how to change/control/increase it?

[Bruno Luong]

If it's not possible, this must be candidate for a frustration thread

Answer 1

[Scott MacKenzie]

s=struct('pi', num2str(pi, 15)); % pi with 15 significant figures
writestruct(s, 'pi.xml');
type pi.xml

Output:

<?xml version="1.0" encoding="UTF-8"?>

<struct>

<pi>3.141592653589793</pi>

</struct>

[Bruno Luong]

I knew this workaround trick.

However not applicable in real life. For example more complicated example

piseries = pi + (0:10);
s=struct('piseries', piseries);
writestruct(s,'pi.xml');
s=readstruct('pi.xml');
s.piseries+1

ans = 1×11

4.1416 5.1416 6.1416 7.1416 8.1416 9.1416 10.1416 11.1416 12.1416 13.1416 14.1416

s=struct('piseries', num2str(piseries,15));
writestruct(s,'pi.xml');
s=readstruct('pi.xml');
s.piseries+1

ans = "3.14159265358979      4.14159265358979      5.14159265358979      6.14159265358979      7.14159265358979      8.14159265358979      9.14159265358979      10.1415926535898      11.1415926535898      12.1415926535898      13.14159265358981"

[Scott MacKenzie]

OK, I get it.

But, what about a workaround to the workaround?

Such as changing

s.piseries+1

to

str2double(split(s.piseries))+1

ans =

4.14159265358979

5.14159265358979

6.14159265358979

7.14159265358979

8.14159265358979

9.14159265358979

10.1415926535898

11.1415926535898

12.1415926535898

13.1415926535898

14.1415926535898

[Bruno Luong]

Thanks for the effort Scott.

To me still not ideal. This XML is used as interface with other SW (otherwise I won't bother with XML). It a pain to minimze the precision output.

[Scott MacKenzie]

Yes, I see your point. I studied the documentation and clearly writestruct is not intended for numeric variables. The focus is on text, and xml in particular. Good luck.