﻿ Function coordcalcextraind()
 Prototype and description of the function coordtransextraind() (Function of the unlock requiring group "Coordinate Transformations")
 ```coordcalcextraind() Calculation of Extra Pparameters independent from coordinate transformations. Meridian Convergence, Origin Center and Geographical Point coordinate. Prototype of the DLL function in C++ syntax (attend lower case!): extern "C" __declspec(dllimport) unsigned long __stdcall coordcalcextraind( double nCoordX, double nCoordY, const char *pszCoord, double nEllHgt, unsigned short nCoordSys, unsigned short nRefSys, unsigned short nUnit, unsigned short nStrip, unsigned long lNoStrip, unsigned long l3D, double *nGeoLon, double *nGeoLat, double *nOrigin, double *nConvergence); Prototype of the DLL function in Visual Objects syntax: _DLL function coordcalcextraind(; nCoordX as real8,; // 8 Byte nCoordY as real8,; // 8 Byte pszCoord as psz,; // 4 Byte, char* nEllHgt as real8,; // 8 Byte nCoordSys as word,; // 2 Byte nRefSys as word,; // 2 Byte nUnit as word,; // 2 Byte nStrip as word,; // 2 Byte lNoStrip as logic,; // 4 Byte l3D as logic,; // 4 Byte nGeoLon ref real8,; // 4 Byte nGeoLat ref real8,; // 4 Byte nOrigin ref real8,; // 4 Byte nConvergence ref real8); // 4 Byte as logic pascal:geodll32.coordcalcextraind // 4 Byte The function calculates the Extra Parameters Meridian Convergence, Origin Center Meridian and Geographical Point Coordinate for a coordinate in any coordinate Reference System (CRS). In contrast to the function coordcalcextra(), the use of the setcalcextra() function is not required. The following Extra Parameters are available: Longitude of the Geographical Point coordinate. Latitude of the Geographical Point coordinate. Longitude of Origin Center. Meridian Convergence at the Geographical Point Coordinates in arbitrary coordinate Reference Systems (CRS) can always be converted into Geographical Point Coordinates. The Longitude of Origin Center is the north-aligned central meridian of the Coordinate System. The Meridian Convergence is often also referred as map convergence or grid convergence. The Meridian Convergence is the angle between the north direction of the coordinate grid and the geographic north direction at the Geographical Point. It can be calculated e.g. for all Mercator and Lambert projections. Note that the calculation of Extra Parameters is not possible with every coordinate transformation. In this case, the values -9999 are returned for the corresponding Extra Parameters. The Meridian Convergence and the Central Meridian are currently supported by the following systems: All Transversal Mercator systems All normal Mercator systems All Lambert Conformal Conic systems If no Extra Parameters could be calculated, the function is terminated with the return value FALSE and the Extra Parameters have the value -9999. For transferring the numerical coordinate nCoordX / nCoordY or the alphanumeric coordinate pszCoord as well as the CRS settings nCoordSys, nRefSys, nUnit, nStrip and lNoStrip please read the detailed notes in the description of the function coordtransex(). The parameters are returned as follows: nCoordX Longitude, East or X component of the numeric coordinate. During processing of an alphanumeric coordinate this parameter is without meaning. The input format of the coordinate (notation) is described in the list "Defaults of the Coordinate Systems". nCoordY Latitude, North or Y component of the numeric coordinate. During processing of an alphanumeric coordinate this parameter is without meaning. The input format of the coordinate (notation) is described in the list "Defaults of the Coordinate Systems". pszCoord Alphanumeric source coordinate. During processing of a numeric coordinate this parameter is without meaning. In this case for pszCoordQ a NULL pointer can be passed. The input format of the coordinate (notation) is described in the list "Defaults of the Coordinate Systems". nEllHgt Ellipsoidical height of the target coordinate (ref) or Z component of a cartesian coordinate. With 3D transformations in the case of using different source and target Reference Systems (nRefSysQ, nRefSysZ), the ellipsoidical height of the target coordinate is calculated. nCoordSys Coordinate System of the coordinate. (see list "Coordinate Reference Systems"). nRefSys Geodetic Reference System of the coordinate. (see list "Coordinate Reference Systems"). nUnit Measurement Unit of the coordinate. 0 The coordinate components are specified in a standard Measurement Unit, as for the Coordinate System preset in GeoDLL. If necessary, they are translated in meters for internal use. (see list "Default settings" [source code: settings_e.txt]). › 0 The coordinate components are specified in a particular Measurement Unit and are translated in meters for internal use. (see list "Coordinate Reference Systems alphabetical" [source: sysalpha_e.txt]). 1000 No effect. The coordinate components are not converted to another Measurement Unit. nStrip Meridian strip to use with the Coordinate System. This parameter has only an effect, if a "Transversal Mercator meridian strip system" is registered in nCoordSys. 0 Using of the leading digits of the easting for the calculation of the natural meridian strip. › 0 Using of the value in nStrip for the calculation of the natural meridian strip. lNoStrip Setting for the suppressing of the meridian strip number in the eastings. This parameter has only an effect, if a "Transversal Mercator meridian strip system" is registered in nCoordSys. TRUE Eastings must be passed without leading meridian strip numbers. FALSE Eastings must be passed with leading meridian strip numbers. l3D Setting for coordinate transformation in 3D mode. When the 3D mode is on, a value must be passed in nEllHgt. TRUE Execution as 3D coordinate transformation. FALSE Execution as 2D coordinate transformation. nGeoLon Geographical longitude in decimal notation calculated from (ref) the coordinate (Geographical Point). Or -9999, if the value could not be calculated. nGeoLat Geographical latitude in decimal notation calculated from (ref) the coordinate (Geographical Point). Or -9999, if the value could not be calculated. nOrigin Longitude of Origin Center. Or -9999, if the value could not be calculated. nConvergence Meridian Convergence at the Geographical Point. (ref) Or -9999, if the value could not be calculated. returnVal In case of error the function returns FALSE, otherwise TRUE. The following topics are explained in detail in the descriptions of the functions coordtransex() .and. coordtrans3dex(): Range validity Notations Standard Reference Systems 3D Coordinate Transformation Unlocking: This function is a component of the unlock requiring function group "Coordinate Transformations". It is unlocked for unrestricted use together with the other functions of the group by passing the unlock parameters, acquired from the software distribution company, trough the function setunlockcode(). Without unlocking only a few function calls for test purposes (shareware principle) are possible. ```