src/jqmath.js
function checkVertStretch (up, dn, g, doP) /* non-MathML */ {
  if (g.nodeName.toLowerCase() == 'mo' && g.childNodes.length == 1) {
    var c = g.firstChild, s = c.data;
    if (c.nodeType == 3 /* Text */ && (up > 0.9 || dn > 0.9)
      && (M.prefix_[s] < 25 || M.postfix_[s] < 25
        || '|\u2016\u221A' /* ‖ &radic; */.indexOf(s) != -1 || doP)) {
      var r = (up + dn) / 1.2, radicQ = s == '\u221A',
        v = (radicQ ? 0.26 : 0.35) + ((radicQ ? 0.15 : 0.25) - dn) / r;
      g.style.fontSize = r.toFixed(3) + 'em';
      g.style.verticalAlign = v.toFixed(3) + 'em';
      g.fmUp = up;
      g.fmDn = dn;
      g.style.display = 'inline-block';
      g.style.transform = g.style.msTransform = g.style.MozTransform =
        g.style.WebkitTransform = 'scaleX(0.5)';
    }
  }
}
function checkVertStretch (up, dn, g, doP) /* non-MathML */ {
  if (g.nodeName.toLowerCase() == 'mo' && g.childNodes.length == 1) {
    var c = g.firstChild, s = c.data;
    if (c.nodeType == 3 /* Text */ && (up > 0.9 || dn > 0.9)
      && (M.prefix_[s] < 25 || M.postfix_[s] < 25
        || '|\u2016\u221A' /* ‖ &radic; */.indexOf(s) != -1 || doP)) {
      var r = (up + dn) / 1.2, radicQ = s == '\u221A',
        v = (radicQ ? 0.26 : 0.35) + ((radicQ ? 0.15 : 0.25) - dn) / r;
      g.style.fontSize = r.toFixed(3) + 'em';
      g.style.verticalAlign = v.toFixed(3) + 'em';
      g.fmUp = up;
      g.fmDn = dn;
      g.style.display = 'inline-block';
      g.style.transform = g.style.msTransform = g.style.MozTransform =
        g.style.WebkitTransform = 'scaleX(0.5)';
    }
  }
}
function checkVertStretch ( up , dn , g , doP ) /* non-MathML */ { if ( g . nodeName . toLowerCase ( ) == 'mo' && g . childNodes . length == 1 ) { var c = g . firstChild , s = c . data ; if ( c . nodeType == 3 /* Text */ && ( up > 0.9 || dn > 0.9 ) && ( M . prefix_ [ s ] < 25 || M . postfix_ [ s ] < 25 || '|\u2016\u221A' /* ‖ &radic; */.i n dexOf(s ) !  - |  d P)) { var r = ( up + dn ) / 1.2 , radicQ = s == '\u221A' , v = ( radicQ ? 0.26 : 0.35 ) + ( ( radicQ ? 0.15 : 0.25 ) - dn ) / r ; g . style . fontSize = r . toFixed ( 3 ) + 'em' ; g . style . verticalAlign = v . toFixed ( 3 ) + 'em' ; g . fmUp = up ; g . fmDn = dn ; g . style . display = 'inline-block' ; g . style . transform = g . style . msTransform = g . style . MozTransform = g . style . WebkitTransform = 'scaleX(0.5)' ; } } }
fmUp is mid-x to outer top, fmDn is mid-x to outer bottom, both approx. & in parent ems
fmUp is mid - x to outer top fmDn is mid - x to outer bottom both approx . & in parent ems