# File lib/maruku/ext/math/mathml_engines/blahtex.rb, line 65
        def convert_to_mathml_blahtex(kind, tex)
    @@BlahtexCache = PStore.new(get_setting(:latex_cache_file))
    
                begin
                        @@BlahtexCache.transaction do 
                                if @@BlahtexCache[tex].nil?
                                        tmp_in = Tempfile.new('maruku_blahtex')
                                                f = tmp_in.open
                                                f.write tex
                                                f.close
                                        tmp_out = Tempfile.new('maruku_blahtex')
        
                                        options = "--mathml"
                                        cmd = "blahtex #{options} < #{tmp_in.path} > #{tmp_out.path}"
                                        #$stderr.puts "$ #{cmd}"
                                        system cmd
                                        tmp_in.delete
                                        
                                        result = nil
                                        File.open(tmp_out.path) do |f| result=f.read end
                                                puts result
                                        
          @@BlahtexCache[tex] = result
                                end
                        
                                blahtex = @@BlahtexCache[tex]
                                doc = Document.new(blahtex, {:respect_whitespace =>:all})
                                mathml = doc.root.elements['mathml']
                                if not mathml
                                        maruku_error "Blahtex error: \n#{doc}"
                                        return nil
                                else
                                        return mathml
                                end
                        end
                        
                rescue Exception => e
                        maruku_error "Error: #{e}"
                end
                nil
        end