Question: When I tried to draw circle on JMapViewer with the following parameters:

Latitude:30.58654740901267
Longitude:31.504483034999993
radius : 100

I got the following gigantic circle
![enter image description here](https://i.stack.imgur.com/7Y3Ig.png)

**What is the measurement unit used for this radius variable ?!!**

**code below**

```
MapMarkerCircle circle = new MapMarkerCircle(c, 100);
Color color = new Color(50, 0, 0,100);
circle.setBackColor(color);
mapViewer.addMapMarker(circle);

```

Answer: 
The `COleDateTime` [(link)](http://msdn.microsoft.com/en-us/library/38wh24td.aspx) and `COleDateTimeSpan` [(link)](http://msdn.microsoft.com/en-us/library/xb7yw6f3.aspx) classes could be used.

```
#include <atlcomtime.h>

COleDateTime dt = COleDateTime::GetCurrentTime();
COleDateTimeSpan span(90, 0, 0, 0);
COleDateTime dt2 = dt - span;

```
```
#include <stdio.h>
#include <string.h>
#include <time.h>

int main(void) {
  time_t t = time(0);                      // NOW
  struct tm tm[1];
  memmove(tm, localtime(&t), sizeof tm);   // convert to struct tm
  tm->tm_mday -= 90;                       // subtract 90 days
  time_t then2 = mktime(tm);               // convert to time_t and normalize
  printf("%s\n", ctime(&then2));
  return 0;
}

```