for_init - Initializes forward projection transformation parameters

SYNTAX

FUNCTION for_init (outsys, outzone, outparm, outdatum, fn27, fn83, iflg, for_trans)
    long        outsys;
    long        outzone;
    double      outparm[15];
    long        outdatum;
    char        fn27[];
    char        fn83[];	
    long       *iflg; 
    long       (*for_trans[MAXPROJ + 1])();

PARAMETERS

outsys (input, long)

Defines the output projection system. Refer to GCTP for valid codes.

outzone (input, long)

Output zone for UTM and State Plane projection systems. For Southern Hemisphere UTM, use a negative zone code. Outzone is ignored for all other projections.

outparm (input, double, length(15))

Array of fifteen projection parameters. These parameters are required to define each map projection. (See Table A)

outdatum (input, long)

Output spheroid. This identifies the semi-major axis and eccentricity that is to be used in the transformation process. Refer to GCTP for valid spheroid codes. If a negative code is entered, elements 1 and 2 of outparm will be used for the semi-major and semi-minor axis (See Table A).

fn27 (input, character, length(*))

Name of the NAD 1927 parameter file for State Plane zone parameters.

fn83 (input, character, length(*))

Name of the NAD 1983 parameter file for State Plane zone parameters.

iflg (output, long)

Error flag after transformation. The error number returned will correspond to the specific error.

for_trans (output, long, length(MAXPROJ + 1))

Function pointer. The pointer to the appropriate forward transformation function is returned in the array for_trans at location outsys. For example, if outsys = TM (see GCTP), the pointer to the function tmfor() would be returned in for_trans[TM]. This can be used to call tmfor() in the following manner:
for_trans [TM](lon, lat, &x, &y);.

DESCRIPTION

for_init() is used to initialize the proper forward projection and to return the pointer to the proper forward transformation routine.

RETURN VALUE

for_init() has no return value.

SPECIAL CONSIDERATIONS:

The for_init() call is for C only.

Table A: Parameters Required for Definition of Map Projections