I am getting GPS data on my window

Actual GPS DATA is stored in these 2 variables

Code:

float landlong= 77.384547E //Realtime Longtitude
float landlat = 12.583857N //RealTime Latitude

But it seems the

**lat & long ** which iam getting from GPS is not coming inside window, its out of window .I checked x & y cordinates it is

Code:

xPos = 1415.7537
yPos = -167.81079

the width & height of my window is

Code:

m_WndWidth=1099
m_WndHeight=673

The formula which iam using to calclulate x & y cordinates is

Code:

xPos = (landlong - m_fMinLon) * (m_WndWidth / (m_fMaxLon - m_fMinLon)) ;
yPos = (landlat - m_fMinLat) * (m_WndHeight / (m_fMaxLat - m_fMinLat)) ;

Code:

**BOTTOM RIGHT CORDINATES**
m_fMaxLat = 12.581369; //MAX lat value
m_fMaxLon = 77.383798;// Max long value
**TOP LEFT CORDINATES**
m_fMinLat = 12.583361;//Min lat value
m_fMinLon = 77.381506;//min long value

Does anyone has the proper formula to calculate X & Y cordinates

Thanks in advance