docs: function plnorm(meanlog, sdlog, lowerTail, logp) {
        var pnorm;
  
        lowerTail = lowerTail !== false;
        logp = logp === true;
  
        if (utils.hasNaN(meanlog, sdlog) || sdlog < 0) {
           return function() { return NaN; };
        }
  
        pnorm = normal.pnorm(meanlog, sdlog, lowerTail, logp);
  
        return function(x) {
           if (utils.hasNaN(x)) { return NaN; }
           if (x <= 0) {
              return lowerTail ? logp ? -Infinity : 0
                               : logp ? 0 : 1;
           }
  
           return pnorm(Math.log(x));
        };
     }