var naming aside, the whitespacing is perplexing:

      U = random_double(); negSreal=-S;
      y1=exp(log(U*Nreal/qu1real)*nmin1inv);
      Vprime = y1 * (-X/Nreal+1.0)*(qu1real/(negSreal+qu1real));
      if(Vprime <= 1.0) break;       y2=1.0; top = -1.0+Nreal;       if(-1+n > S){bottom=-nreal+Nreal;limit=-S+N;}
      else{bottom=-1.0+negSreal+Nreal; limit=qu1;}

Sometimes two statements per line, sometimes one. Sometimes spaces before and after equals, sometimes none. Sometimes multiple ifs, breaks and statements on one line.

It looks like it was copy-pasted from a pdf. Maybe it was.