Note: These formulas have been transcribed from EPSG Guidance Note #7-2. Users are encouraged to use that document rather than the text which follows as reference because limitations in the transcription will be avoided.¶¶From the defining parameters the following constants for the projection may be calculated :¶¶B = {1 + [e^2 * cos^4(latC) / (1 - e^2)]}^0.5¶A=a (1 - e^2 )^0.5 / [ 1 - e^2 sin^2 (latC)]¶gammaO=asin[sin (latC) / B]¶tO =tan(pi / 4 + gamma0 / 2) . [(1 + e sin(latC)) / (1 - e sin (latC))]^(e.B/2) / [tan(pi / 4 + latC/ 2)]^B¶n = sin (latp)¶rO=kp  A / tan (latp)¶¶To derive the projected Southing and Westing coordinates of a point with geographical coordinates (lat, lon) the formulas for the Krovak oblique conic conformal are:¶¶Southing:    X  = FE + r cos theta¶Westing:     Y = FN + r sin theta¶ ¶where¶¶U=2 (atan { tO. tan^B (lat/2 + pi / 4 ) / [(1 + e sin (lat)) / (1 - e sin (lat))]^[e.B/2 ]} - pi / 4)¶V=B (lonO -  lon)¶S=asin [ cos (alphaC) sin ( U ) + sin (alphaC) cos (U) cos (V)]¶D=asin [ cos ( U ) sin ( V ) / cos ( S ) ]¶theta=n D¶r=rO tan^n . (pi / 4 + phi1/ 2) / tan^n ( S/2 + pi / 4 )¶¶The reverse formulas to derive the latitude and longitude of a point from its Southing and Westing values are:¶¶r' =[(X - FE)^2 + (Y - FN)^2]^(1/2)  ¶theta'=arctan [(Y- FN)/(X- FE)]¶D'=theta' / sin ( latp)¶S'=2*{atan[(rO / r' )^(1/n) tan(pi / 4 + latp/ 2)] - pi / 4}¶U'=asin ( cos (alphaC) sin ( S' ) - sin (alphaC) cos (S') cos (D') )¶V'=asin ( cos (S') sin (D') / cos (U'))¶¶Then latitude lat is found by iteration using U' as the value for lat(j-1) in the first iteration:¶lat(j) = 2*(atan{tO^(-1/B) tan^(1/B).( U’/2 + pi / 4 ).[(1 + e sin ( lat( j-1)) / (1 - e sin ( lat(j-1))]^(e/2)} - pi / 4) ¶¶Then¶lon = lonO - V' / B