Read spherical harmonic coefficients from a CHAMP or GRACE-like ascii-formatted file.

## Usage

call SHRead2 (filename, cilm, lmax, gm, r0_pot, error, dot, doystart, doyend, epoch, exitstatus)

## Parameters

filename : input, character(*)
The ascii-formatted filename containing the spherical harmonic coefficients.
cilm : output, real*8, dimension (2, lmax+1, lmax+1)
The spherical harmonic coefficients contained in filename.
lmax : output, integer
The maximum spherical harmonic degree of cilm.
gm : output, real*8
The mass-gravitational constant.
r0_pot : output, real*8
The reference radius of the potential coefficients.
error : output, optional, real*8, dimension (2, lmax+1, lmax+1)
The errors corresponding to the spherical harmonic coefficients cilm.
dot : output, optional, real*8, dimension (2, lmaxout+1, lmaxout+1)
The time derivatives of the spherical harmonic coefficients. The dimension of this array can be smaller than lmax+1.
doystart : output, optional, real*8
The starting time of the solution.
doyend : output, optional, real*8
The ending time of the solution
epoch : output, optional, real*8
The epoch time for the time derivates.
exitstatus : output, optional, integer
If present, instead of executing a STOP when an error is encountered, the variable exitstatus will be returned describing the error. 0 = No errors; 1 = Improper dimensions of input array; 2 = Improper bounds for input variable; 3 = Error allocating memory; 4 = File IO error.

## Description

SHRead2 will read spherical harmonic coefficients from a CHAMP or GRACE-like ascii-formatted file into an array cilm. The errors and time derivatives associated with the coefficients will be read if the optional arrays error and dot are specified, respectively. The staring and ending date of the solution are specified by the optional parameters doystart and doyend, and the epoch of the time derivates is specified by the optional parameter epoch. The maximum spherical harmonic degree is read from the file, and the file does not need to be ordered by angular degree or order.

This routine does not read and output all parameters in the file. Records that are read (and at least partially output) include: EARTH, GGM, SHM, GRCOF2, GRDOTA, CALSDV, gfc, gfct, and dot. Comments specified by the record CMMNT will be print out to the screen, as will the record names that are not currently implemented.

Each line of the file starts with a character string describing what follows.

• EARTH or GGM: GM, R0_POT
• SHM: Maximum spherical harmonic degree of file.
• GRCOF2, CALSDV, or gfc: spherical harmonic coefficients, formatted as (l, m, clm, slm) or (l, m, clm, slm, clm_error, slm_error).