Calculate Surface Area of Lat/ Long - Values

Hi,

I would like to calculate the surface area of lake.

I have two vectors, for the boundary of the lkae, with data in Latitude - Longitudinal format. For some Lat - values I just have NaN - values.

I would like to calculate the surface area with the following command: area = areaint(lat,long)

Getting the following error:

_Error using checklatlon (line 33) Function AREAINT expected its first and second input arguments, LAT and LON, to have NaN-separators in corresponding positions.

Error in areaint (line 61) checklatlon(lat,lon,mfilename,'LAT','LON',1,2);_

Is there any possibility to calculate interpolate the NaN - Values to calculate the above mentioned surface area?