#+BEGIN_HTML
<math xmlns="http://www.w3.org/1998/Math/MathML">
<mrow>
        <msup>
                <mi>a</mi>
                <mn>2</mn>
        </msup>
        <mo>=</mo>
        <mi>b</mi>
</mrow>
</math>
#+END_HTML

(defun org-html-latex-environment (latex-environment contents info)
  "Transcode a LATEX-ENVIRONMENT element from Org to HTML.
CONTENTS is nil.  INFO is a plist holding contextual information."
  (let ((processing-type (plist-get info :with-latex))
        (latex-frag (org-remove-indentation
                     (org-element-property :value latex-environment)))
        (attributes (org-export-read-attribute :attr_html latex-environment)))
    (case processing-type
      ((t mathjax)
       (org-html-format-latex latex-frag 'mathjax info))
;;BEGIN ADD
      ((mathml)
       (org-html-format-latex latex-frag 'mathml info))
;;END ADD
      ((dvipng imagemagick)
       (let ((formula-link
              (org-html-format-latex latex-frag processing-type info)))
         (when (and formula-link (string-match "file:\\([^]]*\\)" formula-link))
           ;; Do not provide a caption or a name to be consistent with
           ;; `mathjax' handling.
           (org-html--wrap-image
            (org-html--format-image
             (match-string 1 formula-link) attributes info) info))))
      (t latex-frag))))

(defun org-html-latex-fragment (latex-fragment contents info)
  "Transcode a LATEX-FRAGMENT object from Org to HTML.
CONTENTS is nil.  INFO is a plist holding contextual information."
  (let ((latex-frag (org-element-property :value latex-fragment))
        (processing-type (plist-get info :with-latex)))
    (case processing-type
      ((t mathjax)
       (org-html-format-latex latex-frag 'mathjax info))
;;BEGIN ADD
      ((mathml)
       (org-html-format-latex latex-frag 'mathml info))
;;END ADD
      ((dvipng imagemagick)
       (let ((formula-link
              (org-html-format-latex latex-frag processing-type info)))
         (when (and formula-link (string-match "file:\\([^]]*\\)" formula-link))
           (org-html--format-image (match-string 1 formula-link) nil info))))
      (t latex-frag))))

(defun org-format-latex-as-mathml (latex-frag latex-frag-type
                                              prefix &optional dir)
  "Use `org-create-math-formula' but check local cache first."
  (let* ((absprefix (expand-file-name prefix dir))
         (print-length nil) (print-level nil)
         (formula-id (concat
                      "formula-"
                      (sha1
                       (prin1-to-string
                        (list latex-frag
                              org-latex-to-mathml-convert-command)))))
         (formula-cache (format "%s-%s.mathml" absprefix formula-id))
         (formula-cache-dir (file-name-directory formula-cache)))

    (unless (file-directory-p formula-cache-dir)
      (make-directory formula-cache-dir t))

    (unless (file-exists-p formula-cache)
      (org-create-math-formula latex-frag formula-cache))

    (if (file-exists-p formula-cache)
        ;; Successful conversion.  Return the link to MathML file.
        (org-add-props
;;BEGIN DEL
;;          (format  "[[file:%s]]" (file-relative-name formula-cache dir))
;;END DEL
;;BEGIN ADD
            (with-temp-buffer (insert-file-contents formula-cache) (buffer-string))
;;END ADD

            (list 'org-latex-src (replace-regexp-in-string "\"" "" latex-frag)
                  'org-latex-src-embed-type (if latex-frag-type
                                                'paragraph 'character)))
      ;; Failed conversion.  Return the LaTeX fragment verbatim
      latex-frag)))

(defun org-format-latex-as-mathml (latex-frag latex-frag-type
                                              prefix &optional dir)
  "Use `org-create-math-formula' but check local cache first."
  (let* ((print-length nil) (print-level nil) ;;必要?
         (mathml (org-create-math-formula latex-frag)))

    ;; Successful conversion.  Return the MathML.
    (if mathml
        (org-add-props
            mathml

            (list 'org-latex-src (replace-regexp-in-string "\"" "" latex-frag)
                  'org-latex-src-embed-type (if latex-frag-type
                                                'paragraph 'character)))
      ;; Failed conversion.  Return the LaTeX fragment verbatim
      latex-frag)))

(defun org-create-math-formula (latex-frag &optional mathml-file)
  "Convert LATEX-FRAG to MathML and store it in MATHML-FILE.
Use `org-latex-to-mathml-convert-command'.  If the conversion is
sucessful, return the portion between \"<math...> </math>\"
elements otherwise return nil.  When MATHML-FILE is specified,
write the results in to that file.  When invoked as an
interactive command, prompt for LATEX-FRAG, with initial value
set to the current active region and echo the results for user
inspection."
  (interactive (list (let ((frag (when (org-region-active-p)
                                   (buffer-substring-no-properties
                                    (region-beginning) (region-end)))))
                       (read-string "LaTeX Fragment: " frag nil frag))))
  (unless latex-frag (error "Invalid LaTeX fragment"))
  (let* ((tmp-in-file (file-relative-name
                       (make-temp-name (expand-file-name "ltxmathml-in"))))
         (ignore (write-region latex-frag nil tmp-in-file))
         (tmp-out-file (file-relative-name
                        (make-temp-name (expand-file-name  "ltxmathml-out"))))
         (cmd (format-spec
               org-latex-to-mathml-convert-command
               `((?j . ,(shell-quote-argument
                         (expand-file-name org-latex-to-mathml-jar-file)))
                 (?I . ,(shell-quote-argument tmp-in-file))
                 (?o . ,(shell-quote-argument tmp-out-file)))))
         mathml shell-command-output)
    (when (org-called-interactively-p 'any)
      (unless (org-format-latex-mathml-available-p)
        (user-error "LaTeX to MathML converter not configured")))
    (message "Running %s" cmd)
    (setq shell-command-output (shell-command-to-string cmd))
    (setq mathml
          (when (file-readable-p tmp-out-file)
            (with-current-buffer (find-file-noselect tmp-out-file t)
              (goto-char (point-min))
              (when (re-search-forward
                     (concat
                      (regexp-quote
                       "<math xmlns=\"http://www.w3.org/1998/Math/MathML\">")
                      "\\(.\\|\n\\)*"
                      (regexp-quote "</math>")) nil t)
                (prog1 (match-string 0) (kill-buffer))))))
    (cond
     (mathml
;;BEGIN DEL
;;      (setq mathml
;;          (concat "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" mathml))
;;END DEL
      (when mathml-file
        (write-region mathml nil mathml-file))
      (when (org-called-interactively-p 'any)
        (message mathml)))
     ((message "LaTeX to MathML conversion failed")
      (message shell-command-output)))
    (delete-file tmp-in-file)
    (when (file-exists-p tmp-out-file)
      (delete-file tmp-out-file))
    mathml))

\begin{displaymath}
T = \left[
\begin{array}{rrr}
\cos \theta & -\sin \theta & 0\\
\sin \theta & \cos \theta & 0\\
0 & 0 & 1
\end{array}
\right]
\end{displaymath}

<script type="text/javascript"
  src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=MML_HTMLorMML">
</script>

(defun org-format-latex-as-mathml (latex-frag latex-frag-type
                                              prefix &optional dir)
  "Use `org-create-math-formula' but check local cache first."
  (let* ((print-length nil) (print-level nil) ;;必要?
         (mathml (org-create-math-formula latex-frag)))

    ;; Successful conversion.  Return the MathML.
    (if mathml
        (org-add-props
            (replace-regexp-in-string "[\n\r]" " " mathml) ;; 改行を削除する。WordPressが<br>を挿入しやがるので

            (list 'org-latex-src (replace-regexp-in-string "\"" "" latex-frag)
                  'org-latex-src-embed-type (if latex-frag-type
                                                'paragraph 'character)))
      ;; Failed conversion.  Return the LaTeX fragment verbatim
      latex-frag)))