MathSqrt

Returns the square root of a number.

double  MathSqrt(
   double  value      // positive number
   );

Parameters

value

[in]  Positive numeric value.

Return Value

Square root of value. If value is negative, MathSqrt returns NaN (indeterminate value).

Note

Instead of MathSqrt() you can use sqrt().

 

Example:

#define GRAPH_WIDTH  750
#define GRAPH_HEIGHT 350
 
#include <Graphics\Graphic.mqh>
 
CGraphic ExtGraph;
//+------------------------------------------------------------------+
//| Script program start function                                    |
//+------------------------------------------------------------------+
void OnStart()
  {
//--- get 11 values from 0 to 10 with step 1
   vector X(11,VectorArange);
   Print("vector X = \n",X);
//--- calculate the square root of each value of the X vector
   X=MathSqrt(X);
   Print("MathSqrt(X) = \n",X);
   
//--- transfer the calculated values from the vector to the array
   double y_array[];
   X.Swap(y_array);
 
//--- draw a graph of the calculated vector values
   CurvePlot(y_array,clrDodgerBlue);
 
//--- wait for pressing the Escape or PgDn keys to delete the graph (take a screenshot) and exit
   while(!IsStopped())
     {
      if(StopKeyPressed())
         break;
      Sleep(16);
     }
 
//--- clean up
   ExtGraph.Destroy();
   /*
   result:
   vector X = 
   [0,1,2,3,4,5,6,7,8,9,10]
   MathSqrt(X) = 
   [0,1,1.414213562373095,1.732050807568877,2,2.23606797749979,2.449489742783178,2.645751311064591,2.82842712474619,3,3.16227766016838]
   */
  }
//+------------------------------------------------------------------+
//| Fill a vector with 'value' in 'step' increments                  |
//+------------------------------------------------------------------+
template<typename T
void VectorArange(vector<T> &vec,T value=0.0,T step=1.0
  { 
   for(ulong i=0i<vec.Size(); i++,value+=step
      vec[i]=value
  }
//+------------------------------------------------------------------+
//| When pressing ESC, return 'true'                                 |
//| When pressing PgDn, take a graph screenshot and return 'true'    |
//| Otherwise, return 'false'                                        |
//+------------------------------------------------------------------+
bool StopKeyPressed()
  {
//--- if ESC is pressed, return 'true'
   if(TerminalInfoInteger(TERMINAL_KEYSTATE_ESCAPE)!=0)
      return(true);
//--- if PgDn is pressed and a graph screenshot is successfully taken, return 'true'
   if(TerminalInfoInteger(TERMINAL_KEYSTATE_PAGEDOWN)!=0 && MakeAndSaveScreenshot(MQLInfoString(MQL_PROGRAM_NAME)+"_Screenshot"))
      return(true);
//--- return 'false' 
   return(false);
  }
//+------------------------------------------------------------------+
//| Create a graph object and draw a curve                           |
//+------------------------------------------------------------------+
void CurvePlot(double &x_array[], double &y_array[], const color colour)
  {
   ExtGraph.Create(ChartID(), "Graphic"000GRAPH_WIDTHGRAPH_HEIGHT);
   ExtGraph.CurveAdd(x_arrayy_arrayColorToARGB(colour), CURVE_LINES);
   ExtGraph.IndentUp(30);
   ExtGraph.CurvePlotAll();
   string text1="Press ESC to delete the graph and stop the script, or";
   string text2="Press PgDn to create a screen, delete the graph and stop the script";
   ExtGraph.TextAdd(549text1ColorToARGB(clrBlack));
   ExtGraph.TextAdd(54,21text2ColorToARGB(clrBlack));
   ExtGraph.Update();
  }
//+------------------------------------------------------------------+
//| Take a screenshot and save the image to a file                   |
//+------------------------------------------------------------------+
bool MakeAndSaveScreenshot(const string file_name)
  {
   string file_names[];
   ResetLastError();
   int selected=FileSelectDialog("Save Picture"NULL"All files (*.*)|*.*"FSD_WRITE_FILEfile_namesfile_name+".png");
   if(selected<1)
     {
      if(selected<0)
         PrintFormat("%s: FileSelectDialog() function returned error %d"__FUNCTION__GetLastError());
      return false;
     }
   
   bool res=false;
   if(ChartSetInteger(0,CHART_SHOW,false))
      res=ChartScreenShot(0file_names[0], GRAPH_WIDTHGRAPH_HEIGHT);
   ChartSetInteger(0,CHART_SHOW,true);
   return(res);
  }

 

Result:

MathSqrt_Screenshot

See also

Real types (double, float), Statistics, Scientific Charts, Client Terminal Properties