MathML, TeX, Math Formatting

Firstly, I don't want to SOLVE equations, I just want to create them.

I've looked through several posts about this and haven't found anything helpful.

I want to create a series of programs (or maybe web apps) to let my students practice solving math problems. I need a way to format certain kinds of math expressions correctly.

Some stuff is easy for format...
x² - 3x + 2 = 0
5x = 10
x - (-4) = 15

But some stuff has no simple (that I know of) way to be displayed in VB...
Simplify (x² - 4) over (x - 2)
Simplify sqrt(50)
Solve x over 10 = 100

I've looked into using MathML, TeX etc. to format the output and maybe use a browser window or rtf but there doesn't seem to be a VB OCX for this.

I want my problems to be randomly generated and then displayed in the correct format. Then the solutions would be generated from the created problem.

Any suggestions?

To display the equations you could create a LaTeX equation string and turn it into a PNG image using a command line parser. I've done this in the past (but not with VB.NET) and I think I used MikTex for this. It has very little to do with VB.NET, except running a command to create the LaTeX file and running another command to turn it into a PNG file.

Of course, the equations have to be in LaTeX form:
\frac{x^2 - 4}{x - 2}
\sqrt{50}
etc...


EDIT
I found my 'project' where I used this. It was a script for Windows Live Messenger Plus! but I never finished it.
I could send you the full (JScript) source but it's alot of stuff you don't need.

The important stuff is this:

Code:

---

// -----------------
                // Create .tex file
                // -----------------
                var texFile = fso.CreateTextFile(path + "\\file.tex", true);
               
                // Write latex 'preamble'
                texFile.WriteLine("\\documentclass{report}\n" +                // we always need to set the documentclass
                                          "\\usepackage{amsmath}\n" +                // use special math package
                                          "\\usepackage{nopageno}\n" +                // get rid of page numbers
                                          "\\setlength\\textwidth{3in}\n" +        // make page width a little smaller to avoid huge windows
                                          "\\setlength\\parindent{0in}\n" +        // no paragraph indent required for us
                                          "\\begin{document}\n");                        // start of document
                var texCode = "";
               
                // Check which equation type to use:
                // - If there are only two tokens, and they are at the start and end of the message,
                //        then we have a single equation without text, so we can use the displaymath equation style
                // - Else, we may have some text between the equations, so we want to use the inline equation style
                if (i===2 && startsWithToken(trim(Message)) && endsWithToken(trim(Message)))
                {
                        Debug.Trace("2 tokens at start and end found --> Using displaymath style.");
                       
                        // Replace first occurence of $$ with the begin displaymath string
                        texCode = Message.replace("$$", "\\begin{displaymath}");
                        // Replace the second (and last) occurence with the end displaymath string
                        texCode = texCode.replace("$$", "\\end{displaymath}");
                }
                else
                {
                        Debug.Trace(i + " tokens found --> Using inline style.");
                        // Replace ALL occurences of $$ with a single $, which automatically transforms the message into valid latex.
                        texCode = Message.replace(/\$\$/g, "$");
                }
               
                texFile.WriteLine(texCode);
                texFile.WriteLine("\n\\end{document}");
                texFile.Close();
               
                Debug.Trace("Tex file created.");
               
               
                // -----------------
                // Create DVI file and PNG file
                // -----------------       
               
                var cmd = "cmd /c " + path.substring(0,2) + " & " +        // start cmd and set drive (C: , D: , etc..)
                                "cd \"" + path + "\" & " +                                // set current directory
                                "latex file.tex & " +                                        // convert tex to dvi
                                "dvipng -T tight -x 1200 -z 1 file.dvi";        // convert dvi to png
                                                       
                Debug.Trace("Executing command: \"" + cmd + "\".");
                var oShell = new ActiveXObject('WScript.Shell');
                oShell.Run(cmd, 0, true);

---

The first part is writing the start of the LaTeX file (you can't just write the equation only, it needs to be in a valid file), things like the packages to use etc.
Then, the "if (i===2 && startsWithToken(trim(Message)) && endsWithToken(trim(Message)))" statement can probably be ignored by you. In this script, it was possible to have an inline equation: ($$ denotes start and end of equation)

Code:

---

This: $$y(x) = 3x^2 + 2$$ is an inline equation

---

or just an equation

Code:

---

$$y(x) = 3 + 4x - 1$$

---

The difference is that, in an inline equation, I use the $ ... $ LaTeX command, for inline equations, and for just an equation I use the \begin{displaymath} and \end{displaymath} commands, which yield some larger and nicer equations.
I assume you don't need any text with your equations, so you can always use the \begin{displaymath} and \end{displaymath} commands.

Finally, I run two commands (at the same time, after setting the working directory):

Code:

---

latex file.tex

---

this creates a .dvi file from the .tex file

Code:

---

dvipng -T tight -x 1200 -z 1 file.dvi

---

this converts file.dvi into a PNG image using some properties. For these commands you need MikTex and DviPng (I think both come togheter but I dunno..)


Hope that helps!

In VB.NET that could look something like this

vb.net Code:

Private Sub CreatePng(ByVal equation As String)
    
    Dim texFile As New StringBuilder()
    
    'Write LaTeX 'preamble'
    texFile.AppendLine("\documentclass{report}")
    texFile.AppendLine("\usepackage{amsmath}")  'some math functions
    texFile.AppendLine("\usepackage{nopageno}")  'no page numbers
    texFile.AppendLine("\setlength\textwidth{3in}")  'this doesn't look like a valid command but it seems to have worked :S
    texFile.AppendLine("\setlength\parindent{0in}")
    texFile.AppendLine("\begin{document}")
    
    'add the equation
    texFile.AppendLine("\begin{displaymath}" & equation & "\end{displaymath}")
    
    'end the document 
    texFile.AppendLine("\end{document}")
    
    'save it. Perhaps you should use a temporary file (in the Temp folder) for this!
    System.IO.File.WriteAllText("C:\equation.tex", texFile.ToString)
    
    'Convert to DVI
    Process.Start("latex C:\equation.tex")
    
    'And to PNG
    Process.Start("dvipng -T tight -x 1200 -z 1 C:\equation.dvi")
End Sub

Not too sure if the commands at the end would work like this... But it's something like that anyway.


After that, just display the 'equation.png' file in a PictureBox.
Of course, the users of this application need to be able to execute the 'latex' and 'dvipng' commands so they need to have latex installed!

Thanks for your response. I'll use it if things must go that way. But....

Is there no way to create a TeX string and use somebody's OCX to covert it to a pgn image (or bitmap or jpg) - or even better: some text or HTML - and display that?

Surely someone has written a MathML or TeX OCX that can be used for this kind of stuff. I don't want to rely on any external programs.

Not too sure what you mean by an 'OCX'. I know the term OCX from VB6 where they were something like DLL's but other than that I don't know what they are.

If you mean some code somebody has written in VB.NET, then I highly doubt it. I don't think there is anything available for VB.NET or C#.NET even that will convert a latex string into an image without using some kind of external tools (like Miktex).

Thanks for the help, Nick. I'd rather go with an all-in-one solution and not need to depend on extra software. I still might go with your idea if all else fails.

Any one else want to chime in?

PS to Nick.
I have an exchange student this year from the Netherlands. She's a pretty good kid. I haven't learned much dutch but my spanish is getting better. (I have a student from Venezuela, too.)

I have one made. will post or upload to this site.

I have a program that I made. Written in Vb6.
you can activate it with a checkmark to keep program floating, You type in the textbox, example given: sqrt 25 and press enter.
It will format the sentence and send to a server and the server gives you a picture in picture box.
Picture box follows the mouse cursor for you to put any where in a environment where you can "draw" with mouse.
Once you place the picture where you want it. Press enter and it start drawing it for you. I use it for myself in Real Time Board for tutoring math across the internet. Also recently added a grid maker to help in Geometry. I can not figure a way to up load to here.

Not trying to direct traffic away from this site, since I can not find a way to upload to this site, may I humbly direct you to Planet Source Code and look for White board or you can Google it and look for math LaTek Vb6 formula generator by soundminded. If I have broen any rules, please accept my apologies, and will the proper people please contact me as I wish to share this program and source written in Vb6. I had this IDE since 1994. Yes, call me old and old fashioned.