fixes #53 correctly handle sphirical sinu

    },

    inverse: function(p) {

      var lat, temp, lon;

      var lat, temp, lon, s;

      /* Inverse equations

    -----------------*/

      p.x -= this.x0;

      lon = p.x / this.a;

      p.y -= this.y0;

      lat = p.y / this.a;

      if (this.sphere) {

        p.y /= this.C_y;

        lat = this.m ? Math.asin((this.m * p.y + Math.sin(p.y)) / this.n) : (this.n !== 1 ? Math.asin(Math.sin(p.y) / this.n) : p.y);

        lon = p.x / (this.C_x * (this.m + Math.cos(p.y)));

        lat /= this.C_y;

        lon = lon / (this.C_x * (this.m + Math.cos(lat)));

        if(this.m){

          lat = common.asinz((this.m * lat + Math.sin(lat)) / this.n);

        }else if(this.n !== 1){

          lat = common.asinz(Math.sin(lat) / this.n);

        }

        lon = common.adjust_lon(lon + this.long0);

        lat = common.adjust_lat(lat);

      }

      else {

        lat = common.pj_inv_mlfn(p.y / this.a, this.es, this.en);

        var s = Math.abs(lat);

        s = Math.abs(lat);

        if (s < common.HALF_PI) {

          s = Math.sin(lat);

          temp = this.long0 + p.x * Math.sqrt(1 - this.es * s * s) / (this.a * Math.cos(lat));