fmath for ck editor

I want to add equations in ck editor.But I am trying to use fmath plugin in ck editor,But I am unable to do that.

CKEDITOR.plugins.addExternal('fmath_formula', 'plugins/fmath_formula/', 'plugin.js');

// Add the button to toolbar
config.toolbar = [
['Templates', 'Styles', 'Format', 'Font', 'FontSize', 'TextColor', 'BGColor', 'Maximize', 'Image'],
['Source'],
['Bold', 'Italic', 'Underline', 'Strike', '-', 'Subscript', 'Superscript', '-', 'fmath_formula'],
['Table', 'HorizontalRule'],
['NumberedList', 'BulletedList', '-', 'Outdent', 'Indent', 'Blockquote']
]

};

mypage.js
$(document).ready(function () {

//CKEDITOR.plugins.addExternal('fmath_formula', 'plugins/fmath_formula/', 'plugin.js');

var ckeditor_config = {
width: 670,
height: 220,
toolbarCanCollapse: false,
removePlugins: 'elementspath',
toolbar: [['Bold', 'Italic', 'Underline', '-',
'JustifyLeft', 'JustifyCenter', 'JustifyRight', '-',
'NumberedList', 'BulletedList', '-', 'Indent', 'Outdent', '-', 'Link', 'Unlink', '-',
'Image', 'Video', 'Templates', '-', 'Preview', 'Print', '-', 'Source', 'Styles', 'Format', 'FontSize', 'Font', 'TextColor', 'BGColor', 'fmath_formula']],
uiColor: '#9AB8F3'
};
$("textarea#editor1").val("").ckeditor(ckeditor_config);

});