Построитель графиков на C#

>                  begin_ = begin*10;

                  end_ = end*10;

                  step_ = (float)step*10; 

                  for(float i=begin_;i<=end_;i+=step_)

                  {

                        for(float j=begin_;j<=end_;j+=step_)

                        {  

                              num++; 

                              vlist_local[num].x = i*0.1f;

                              vlist_local[num].z = j*0.1f;

                              vlist_local[num].y = sa.Function(vlist_local[num].x, vlist_local[num].z, expression, 2);     

                              vlist[num].x = vlist_local[num].x;

                              vlist[num].y = vlist_local[num].y;

                              vlist[num].z = vlist_local[num].z;

                        }

                  }

                        num_vert = num;

            }

            public void CalculateCoordParametricFunc(ref int num_vert, string expression1, string expression2, string expression3)

            {

                  SyntaxAnalyzer sa = new SyntaxAnalyzer();

                  int num = -1;//счетчик вершин

                  //здесь _begin исправить

                  float begin_, end_, step_;

                  float a, b;

                  begin_ = begin*10;

                  end_ = end*10;

                  step_ = (float)step*10; 

                  for(float i=begin_;i<=end_;i+=step_)

                  {

                        for(float j=begin_;j<=end_;j+=step_)

                        {  

                              num++;

                              a = i*0.1f;

                              b = j*0.1f;

                              vlist_local[num].x = sa.Function(a, b, expression1, 2);

                              vlist_local[num].y = sa.Function(a, b, expression2, 2);

                              vlist_local[num].z = sa.Function(a, b, expression3, 2);

                        }

                  } 

                  num_vert = num;

            }

            public void AutomaticChoiceInterval()

            {

                  bool is_del = false;//существует ли в текущем выражении знак '/'(разделить)

                  bool is_y = false;//существует ли в текущем выражении 'y'

                  bool is_sqrt = false;//существует ли в текущем выражении 'sqrt'

                  bool sq = false;

                  int i=0, k=0;

                  float f=-1;

                  string temp;

                  is_y = simbol_find(expression1,'y', ref i);

                  i=0;

                  is_del = simbol_find(expression1,'/', ref i);

                  i=0;

                  sq = simbol_find(expression1,'q', ref i); 

                  while(sq == true)

                  {

                        is_sqrt = true;

                        //Вычисляем  все подкоренные выражения

                        while(expression1[k] != ')')

                        {

                              k++;

                              continue;

                        }

                        SyntaxAnalyzer sa = new SyntaxAnalyzer();

                        temp = expression1.Substring(i+3, k-(i+2));

                        temp = temp+" ";

                        f = sa.Function(-3, 0, temp, 1);

                        if(f<0)

                              break; 

                        sq = simbol_find(expression1,'q', ref k);

                        i=k;

                  }

                  int p=0,l=0;

                  //Выбор диапозона  значений 

                  if(TypeFunction == "f(x)=")

                  {

                        i=0; 

                        //Если в  выражении корень и подкоренное  выражение больше нуля

                        if(is_sqrt == true && f>0)

                        {

                              _begin =  -12;

                              _end = 12;

                              _step = 0.1;

                        }

                              //Если в  выражении корень и подкоренное  выражение меньше нуля

                        else if(is_sqrt == true && f<0)

                        {

                              _begin = 0;

                              _end = 12;

                              _step = 0.1;

                        }

                        else if(is_del == true || simbol_find(expression1,'i', ref i) || simbol_find(expression1,'o', ref p) || simbol_find(expression1,'t', ref l))

                        {

                              _begin = -12;

                              _end = 12;

                              _step = 0.1;

                        }

                        else if(is_sqrt == false)

                        {

                              _begin = -3;

                              _end = 3;

                              _step = 0.1;

                        }

                  }

                  else if(TypeFunction == "f(x,y)=")

                  {

                        _begin = -12;

                        _end = 12;

                        _step = 1;

                  }

            } 

            public void InitGraph()//Camera cam, Vector cam_pos, Vector cam_dir

            {

                  SyntaxAnalyzer sa = new SyntaxAnalyzer();

                  int num_vert=0; 

                  if(TypeFunction == "f(x)=")

                  {

                        CalculateCoord2D(ref num_vert, expression1);

                  }

                  else if(TypeFunction == "f(x,y)=")

                  {

                        CalculateCoord3D(ref num_vert, expression1);

                  }

                  else if(TypeFunction == "Параметрический вид")

                  {

                        CalculateCoordParametricFunc(ref num_vert, expression1, expression2, expression3);

                  } 

                  //сохраняем  кол-во вершин в num_vertices

                  num_vertices = num_vert; 

                  //Инициализируем  объект камера

                  cam.InitCamera(cam.pos, cam.dir, world_pos.x*2, world_pos.y*2); 

            }

            public void TransformGraph(Matrix mrot) //поворот графика

            {  

                  float _scale_x = 0;

                  float _scale_y = 0;