This dataset is not intended for users, but rather for internal use
within the gsw package. The dataset stores the 1.4M lookup
table defined in the 8.3M file src/gsw_saar_data.c in the C
library. (The .c file exceeds CRAN limitations on size.)
The data are designed to replace C elements defined as below
in src/gsw_saar_data.c:
static int gsw_nx=91, gsw_ny=45, gsw_nz=45;
static double longs_ref[91];
static double lats_ref[45];
static double p_ref[45];
static double ndepth_ref[4095];
static double saar_ref[184275];
static double delta_sa_ref[184275];
R storage is in a list named saar, with elements named
as in the C code, i.e. gsw_nx etc.
C storage for these variables is allocated as needed,
and the data are inserted, when gsw is launched.
Thus, the existing C library code "knows" about the data
as local storage, which keeps alterations to the C library to
a minimum.
The code used to create the RDA file (using the Fortran data file, version 3.0.3) is given below.
gsw_nx <- 91
gsw_ny <- 45
gsw_nz <- 45
f <- file("~/src/gsw_fortran_v3_03/gsw_data_v3_0.dat", "r")
longs_ref <- scan(f, double(), n=gsw_nx)
lats_ref <- scan(f, double(), n=gsw_ny)
p_ref <- scan(f, double(), n=gsw_nz)
ndepth_ref <- scan(f, double(), n=gsw_nx*gsw_ny)
saar_ref <- scan(f, double(), n=gsw_nx*gsw_ny*gsw_nz)
delta_sa_ref <- scan(f, double(), n=gsw_nx*gsw_ny*gsw_nz)
saar <- list(gsw_nx=gsw_nx, gsw_ny=gsw_ny, gsw_nz=gsw_nz,
longs_ref=longs_ref, lats_ref=lats_ref, p_ref=p_ref, ndepth_ref=ndepth_ref,
saar_ref=saar_ref, delta_sa_ref=delta_sa_ref)
save(saar, file="saar.rda")
tools::resaveRdaFiles("saar.rda")
close(f)