MathML to/from Plain Text Converter

• Download MathML_ToFrom_String_javascript.zip - 9.8 KB
• Download MathML_ToFrom_StringCore.zip 1005.3 KB
• Download demo

Introduction

There seem to be few resources converting MathML code into plain text. A good reason is there is no consensus in how to format some math expressions. But for many expressions involving (+,-,/,*,^,=) operators, here is one possible converter.

The Classes Engaged

• Class MathToString prepares the string with the MathML code so that class ParseML can perform the detailed parsing.

Preparation

First, the spaces are replaced by empty strings and some special characters are replaced too. Also, some tags not involved in the math expression, like style tags, are removed. Then the code goes over from the most insider <mfrac>...</mfrac>, <msup>...</msup>, <mrow>...</mrow>, <msqrt>...</msqrt> tags to the most outer, being parsed and replaced, enclosing them in between special characters so that later they can be recovered by ParseML class.

Using the Code

To convert, just call the shared method MathToString.convertToString():

Dim converted as String = MathMLToString.convertToString(MathMLcodeToConvert)

To convert text to MathML, call convertStringToMathML().

Basic Principles

The parsing method is a recursive-descent parsing: Parsing Expressions by Recursive Descent.

Evaluation method E calls T for any addition or subtraction, but T calls first F for any multiplication or subtraction, and F calls first P for any power possible power operation. P calls first v to get next token. If there is a "(" token, v calls recursively to T.

E --> T {( "+" | "-" ) T}
T --> F {( "*" | "/" ) F}
F --> P ["^" F]
P --> v | "(" E ")" | "-" T

History

• 12^th May, 2022: Initial version

Version 1.0.3.0

Now, demo zip file contains a setup file.

JavaScript, .NET, and Core applications have been re-coded, because MathML is an application of XML and to reflect tags can be 'recursively' nested, I mean, an element can appear inside itself or any level below its children elements. For example:

<mfrac>
   <mrow>
     <mi>-1</mi>
   </mrow>
   <mn>
     <mn>3</mn>
   </mn>
</mfrac>

Version 2.0.0.0 (2024-03-25)

The code has been rewritten, improved and expanded. For example, it now supports including equations in LaTex language such as the following:

\begin{array}{*{20}c} {x = \frac{{ - b \pm \sqrt {b^2 - 4ac} }}{{2a}}} &
{{\text{when}}} & {ax^2 + bx + c = 0} \\ \end{array}

To this end, by putting the equation in LaTex in the MathML textbox and clicking on 'Convert to Plain Text' the Latex code is replaced by its translation to MathML and converted to plain text.

Version 2.0.5.0 (2024-04-17)

Some more samples have been added.

Arranges have been made so that square and curly brackets are reflected in the conversion.

ConvertStringToMathML.EvaluateFromInnerToOuter() is a new method and, as its name indicates, it examines from most inner paired parentheses and/or brackets to most outer.