code: function transpose() {
           var tmp,
               a = this.val;
           tmp = a[1];
           a[1] = a[3];
           a[3] = tmp;
           tmp = a[2];
           a[2] = a[6];
           a[6] = tmp;
           tmp = a[5];
           a[5] = a[7];
           a[7] = tmp;
           return this;
         }
docs: Transpose the value of this matrix.
  @name transpose
  @memberOf me.Matrix2d
  @function
  @return {me.Matrix2d} Reference to this object for method chaining