MaRC Files

• Reduced footprint of the MaRC program (marc) and library (libMaRC). For example, including both the MaRC library and program, the static footprint was reduced by 28% for a 64-bit Linux build with g++ 7.2 when comparing total sizes returned by the size command.

• Data scaling values, i.e. BSCALE and BZERO, as well as the physical data unit (BUNIT) are now automatically written to the map FITS header when possible. This allows FITS reading and viewing software to automatically provide the actual physical value to the user, instead of forcing the user to manually scale the map data. Currently this only applies to single plane maps containing one of the MaRC virtual images (MU, MU0, PHASE, LATITUDE or LONGITUDE).

Maps with multiple planes currently write the scaling values as free-form text across several HISTORY cards in the FITS header instead of standalone BSCALE, BZERO and BUNIT cards. In this case, data scaling of map values to physical values must generally be performed manually.

• Corrected automatic offset calculation for LONGITUDE map planes when creating integer typed maps. Longitude values closer to 360 degrees are no longer cutoff. Be aware that an offset must be applied to convert from the map longitude value to the physical longitude value. See the generated map FITS header to obtain the offset (BZERO) value.

• Further expanded the MaRC test suite (try "make check").

• The MU, MU0 and PHASE virtual images may now contain all cosine values i.e. the interval [-1, 1], and are no longer limited to positive values alone. There was no real need to drop the negative values. To obtain the old behavior where only cosine values [0, 1] were mapped set the DATA_MIN keyword for the MU, MU0 and PHASE map plane entries in your MaRC input file to zero, e.g.:

    PLANE:
            DATA_MIN: 0
            MU: ...
  

• The PHASE virtual image no longer ties the existence of a datum to a positive cosine of the emission of the angle (μ), meaning cosine of phase angle data will be plotted in areas of the map where μ < 0.

• Improved speed of MU, MU0 and PHASE virtual image generation by up to 100% by dropping a redundant data "visibility" check.

• Slightly improved overall MaRC performance by leveraging link-time optimization on some platforms.

• Corrected problem in conformal (Mercator and Polar Stereographic) maps that prevented calculation of latitudes for the entire map from completing in some cases.

• Dropped references to "transverse" in documentation related to the Mercator projection. MaRC's Mercator projection is the regular variant not the transverse one.

• Improved accuracy of conformal maps through root finding improvements.

• Fixed memory violations in conformal maps.