MAPTRI(3NCARG)

✨ MAPTRI ✨

okay so bestie, welcome to the NCAR GRAPHICS corner of the manual, where we do ✨map math✨. this one is MAPTRI from section 3NCARG, and it is literally the undo button for map projections. no cap.

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💖 NAME 💖

MAPTRI — performs inverse transformations. that's it, that's the whole job. it takes a point that's already been squished onto your map and tells you where on the actual globe it lives. 🗺️✨

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🌸 SYNOPSIS 🌸

CALL MAPTRI (UVAL,VVAL,RLAT,RLON)

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🦋 C-BINDING SYNOPSIS 🦋

#include <ncarg/ncargC.h>

void c_maptri (float uval, float vval, float *rlat,
float *rlon)

yes bestie, there's a C version, it's giving bilingual 👑

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💅 DESCRIPTION 💅

UVAL and VVAL

these are input expressions, of type REAL, and together they define the point (UVAL,VVAL) — aka the projection in the u/v plane of the point whose latitude and longitude you're dying to know. 🫶

heads up: the units of UVAL and VVAL depend on the projection. it's not one-size-fits-all, it's one-size-fits-your-projection. iykyk.

RLAT and RLON

these are output variables, of type REAL, and they are the latitude and longitude (respectively) of the point, in degrees. 🌍

• RLAT will be between -90. and +90., inclusive.
• RLON will be between -180. and +180., inclusive.

and now the part we gotta talk about, bestie 😭 — if the point (UVAL,VVAL) is not the projection of some point of the globe, or it's outside the boundary of the map, then RLAT and RLON get returned equal to 1.E12. that's the "girl this doesn't exist" number. it's iconic but also kind of a jumpscare, so check for it. 💀

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🌈 C-BINDING DESCRIPTION 🌈

the C-binding argument descriptions are the same as the FORTRAN argument descriptions. same vibes, different syntax, we love consistency 💜

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⭐ EXAMPLES ⭐

use the ncargex command to see the following relevant examples: ccpmpxy, mpex10. go look, they're cute, they'll show you the whole thing in action. ✨

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🎀 ACCESS 🎀

to use MAPTRI or c_maptri, load the NCAR Graphics libraries ncarg, ncarg_gks, and ncarg_c — preferably in that order. the order matters bestie, do not freestyle it 🙈

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💖 SEE ALSO 💖

Online: ezmap, ezmap_params, mapaci, mapbla, mapblm, mapdrw, mapeod, mapfst, mapgci, mapgrd, mapgrm, mapgtc, mapgti, mapgtl, mapgtr, mapint, mapiq, mapiqa, mapiqd, mapiqm, mapit, mapita, mapitd, mapitm, maplbl, maplmb, maplot, mappos, maproj, maprs, maprst, mapsav, mapset, mapstc, mapsti, mapstl, mapstr, maptra, maptrn, mapusr, mapvec, mpchln, mpfnme, mpgetc, mpgeti, mpgetl, mpgetr, mpglty, mpiaty, mpifnb, mpilnb, mpiola, mpiosa, mpipai, mpipan, mpipar, mpisci, mplnam, mplndm, mplndr, mplnri, mpname, mprset, mpsetc, mpseti, mpsetl, mpsetr, supmap, supcon, ncarg_cbind

that's a whole friend group, fr fr 🫂

Hardcopy: NCAR Graphics Contouring and Mapping Tutorial 📚

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👑 COPYRIGHT 👑

Copyright (C) 1987-2009 University Corporation for Atmospheric Research The use of this Software is governed by a License Agreement.

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and that's the whole page, bestie!! 🎉 this version is from UNIX, dated March 1993, and it's page MAPTRI(3NCARG) of the NCAR GRAPHICS manual. slay, go map something, you ate 💅💖