function fncSr = fncSpeedRef(param,r,v)
  sp = [1, 2]; % 1 = x; 2 = y
  if (length(param) == 4)
                                % 'xsin' / 'xcos'
    strSinOcos = strcat(sprintf("%s", param(2:length(param))));

    if (param(1) == 'x')
      strSfx = strcat(sprintf("%i*%s(%i*t)",r,strSinOcos,v));
      strSfy = strcat(sprintf("%i",r));
                                % 'ysin' / 'ycos'
    elseif (param(1) == 'y')
      strSfx = strcat(sprintf("%i",r));
      strSfy = strcat(sprintf("%i*%s(%i*t)",r,strSinOcos,v));
    endif

  elseif (param(1) == 'c')
    if(param(2) == 'c')
                                %'circle'
      strSfx = strcat(sprintf("%i*cos(%i*t)",r,v));
      strSfy = strcat(sprintf("%i*sin(%i*t)",r,v));

    else
      strSfx = strcat(sprintf("%i*sin(%i*t)",r,v));
      strSfy = strcat(sprintf("%i*cos(%i*t)",r,v));
    endif

  elseif (param == 's')
    strSfx = strcat(sprintf("%i",r));
    strSfy = strcat(sprintf("%i",v));
  else
    printf("Karepmu opo ? \n\n bukak fungsi speedRef sek diwoco komen e \n\n");
  endif

  strAll = strcat("fncSr = @(t) [",strSfx, ";\ ", strSfy, "];");
  %% printf(strAll)
  eval(strAll);

  %% spx = sfx(t);
  %% spy = sfy(t);
endfunction