iink SDK Web

Recognising letters within math

We are using the iink Web SDK to successfully convert math notation, however is there a gesture or otherwise to tell the SDK to recognise the letter "O" or "S"?

I cannot see a way to differentiate the user drawing an O instead of a 0 or an S instead of a 5. Sometimes I am able to draw an S very carefully, but I can never get the recogniser to pick up the letter "O", it always returns a "0"

Hi Ryan,

Thank you for your question.

In math part, without any other context, the math recognizer is very likely to return a "0" indeed, as for an isolated symbol it is pretty difficult to make the difference between a 0 and a O, even for humans. So in a math context, the recognizer promotes the 0 digit.

But if you add some context, like a digit in subscript or superscript, the recognized result will be updated to the letter "O".

You can find as attached image a test I did with the math demo:


When I started writing the "circle" a 0 was recognized but when adding the 1 subscript, recognition result is updated to O1.

If you have specific situation where you want to recognize the letter "O" rather than the digit "0", you may consider using a specific math grammar.

Best regards,


Hi Gwenaëlle,

I appreciate that 0 and O are similar, but was wondering if there was any way that the user could indicate the difference between them using a gesture? e.g. Forcing the user to draw a slashed zero ( ø ) to draw a 0, then a circle maps to an O.

The problem we have is that in Scandinavian languages, O is frequently used as the variable for area:

Therefore many formulas start with "O =". As you can imagine, the SDK translates this to "0 =" which makes sense, but for the majority of users in these languages would be the unexpected result


Hi Ryan,

Thank you for your update.

Sharing with us this Scandinavian math use case is very interesting to help our R&D improve our technology.

We have transmitted this use case to our product line and R&D, as a long term improvement of the math recognizer.

Unfortunately, we don't see any way with our current APIs to cope with this use case, as the math recognizer does not support the slashed zero symbol ( ø ) , nor the slash gesture.

Best regards,


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