Fortran Interface

Singularity-EOS provides a Fortran interface which can be enabled with the CMake SINGULARITY_USE_FORTRAN option. The interface provides Fortran bindings to the C++ EOS types and gives access to both initialization functions and EOS evaluation functions.

The Fortran interface is defined in singularity-eos/eos/singularity_eos.f90.

Modules

The Fortran interface consists of two modules:

singularity_eos_types - Defines the data types used by the interface
singularity_eos - Contains the functions for initializing and using EOS models

Data Types

type :: sg_eos_ary_t
  type(c_ptr) :: ptr = C_NULL_PTR
end type sg_eos_ary_t

The sg_eos_ary_t type is a wrapper around a C pointer to the underlying EOS object.

Initialization Functions

integer function init_sg_eos_f(nmat, eos) result(err)
  integer(kind=c_int), intent(in) :: nmat
  type(sg_eos_ary_t), intent(in)  :: eos
end function init_sg_eos_f

Initializes the EOS array with the specified number of materials.

The following functions are available for initializing EOS models:

Ideal Gas

integer function init_sg_IdealGas_f(matindex, eos, gm1, Cv, &
                                   sg_mods_enabled, sg_mods_values) &
  result(err)
  integer(c_int), value, intent(in) :: matindex
  type(sg_eos_ary_t), intent(in)    :: eos
  real(kind=8), value, intent(in)   :: gm1, Cv
  integer(kind=c_int), dimension(:), target, optional, intent(inout) :: sg_mods_enabled
  real(kind=8), dimension(:), target, optional, intent(inout)        :: sg_mods_values
end function init_sg_IdealGas_f

Initializes an Ideal Gas EOS model at the specified material index.

matindex: Material index (1-based in Fortran)
eos: EOS array
gm1: Gamma minus 1 (γ-1)
Cv: Specific heat at constant volume
sg_mods_enabled: Optional array for enabling modifiers
sg_mods_values: Optional array for modifier values

Gruneisen

integer function init_sg_Gruneisen_f(matindex, eos, C0, s1, s2, s3, G0, b, &
                                    rho0, T0, P0, Cv, sg_mods_enabled, &
                                    sg_mods_values) &
  result(err)
  integer(c_int), value, intent(in) :: matindex
  type(sg_eos_ary_t), intent(in)    :: eos
  real(kind=8), value, intent(in)   :: C0, s1, s2, s3, G0, b, rho0
  real(kind=8), value, intent(in)   :: T0, P0, Cv
  integer(kind=c_int), dimension(:), target, optional, intent(inout) :: sg_mods_enabled
  real(kind=8), dimension(:), target, optional, intent(inout)        :: sg_mods_values
end function init_sg_Gruneisen_f

Initializes a Gruneisen EOS model at the specified material index.

matindex: Material index (1-based in Fortran)
eos: EOS array
C0: Bulk sound speed
s1, s2, s3: Coefficients for the shock Hugoniot
G0: Gruneisen parameter
b: Gruneisen parameter correction
rho0: Reference density
T0: Reference temperature
P0: Reference pressure
Cv: Specific heat at constant volume
sg_mods_enabled: Optional array for enabling modifiers
sg_mods_values: Optional array for modifier values

Jones-Wilkins-Lee

integer function init_sg_JWL_f(matindex, eos, A, B, R1, R2, w, rho0, Cv, &
                              sg_mods_enabled, sg_mods_values) &
  result(err)
  integer(c_int), value, intent(in) :: matindex
  type(sg_eos_ary_t), intent(in)    :: eos
  real(kind=8), value, intent(in)   :: A, B, R1, R2, w, rho0, Cv
  integer(kind=c_int), dimension(:), target, optional, intent(inout) :: sg_mods_enabled
  real(kind=8), dimension(:), target, optional, intent(inout)        :: sg_mods_values
end function init_sg_JWL_f

Initializes a JWL (Jones-Wilkins-Lee) EOS model at the specified material index.

matindex: Material index (1-based in Fortran)
eos: EOS array
A, B: JWL parameters
R1, R2: JWL parameters
w: JWL parameter
rho0: Reference density
Cv: Specific heat at constant volume
sg_mods_enabled: Optional array for enabling modifiers
sg_mods_values: Optional array for modifier values

Davis Products

integer function init_sg_DavisProducts_f(matindex, eos, a, b, k, n, vc, pc, &
                                        Cv, sg_mods_enabled, &
                                        sg_mods_values) &
  result(err)
  integer(c_int), value, intent(in) :: matindex
  type(sg_eos_ary_t), intent(in)    :: eos
  real(kind=8), value, intent(in)   :: a, b, k, n, vc, pc, Cv
  integer(kind=c_int), dimension(:), target, optional, intent(inout) :: sg_mods_enabled
  real(kind=8), dimension(:), target, optional, intent(inout)        :: sg_mods_values
end function init_sg_DavisProducts_f

Initializes a Davis Products EOS model at the specified material index.

matindex: Material index (1-based in Fortran)
eos: EOS array
a, b, k, n: Davis Products parameters
vc: Critical specific volume
pc: Critical pressure
Cv: Specific heat at constant volume
sg_mods_enabled: Optional array for enabling modifiers
sg_mods_values: Optional array for modifier values

Davis Reactants

integer function init_sg_DavisReactants_f(matindex, eos, rho0, e0, P0, T0, &
                                         A, B, C, G0, Z, alpha, Cv0, &
                                         sg_mods_enabled, sg_mods_values) &
  result(err)
  integer(c_int), value, intent(in) :: matindex
  type(sg_eos_ary_t), intent(in)    :: eos
  real(kind=8), value, intent(in)   :: rho0, e0, P0, T0, A, B, C, G0, Z
  real(kind=8), value, intent(in)   :: alpha, Cv0
  integer(kind=c_int), dimension(:), target, optional, intent(inout) :: sg_mods_enabled
  real(kind=8), dimension(:), target, optional, intent(inout)        :: sg_mods_values
end function init_sg_DavisReactants_f

Initializes a Davis Reactants EOS model at the specified material index.

matindex: Material index (1-based in Fortran)
eos: EOS array
rho0: Reference density
e0: Reference specific internal energy
P0: Reference pressure
T0: Reference temperature
A, B, C: Davis Reactants parameters
G0: Gruneisen parameter
Z: Davis Reactants parameter
alpha: Davis Reactants parameter
Cv0: Specific heat at constant volume
sg_mods_enabled: Optional array for enabling modifiers
sg_mods_values: Optional array for modifier values

Noble-Abel

Note

This model is only available when SINGULARITY_USE_V_AND_V_EOS is ON.

integer function init_sg_NobleAbel_f(matindex, eos, gm1, Cv, &
                                   bb, qq, &
                                   sg_mods_enabled, sg_mods_values) &
  result(err)
  integer(c_int), value, intent(in) :: matindex
  type(sg_eos_ary_t), intent(in)    :: eos
  real(kind=8), value, intent(in)   :: gm1, Cv, bb, qq
  integer(kind=c_int), dimension(:), target, optional, intent(inout) :: sg_mods_enabled
  real(kind=8), dimension(:), target, optional, intent(inout)        :: sg_mods_values
end function init_sg_NobleAbel_f

Initializes a Noble-Abel EOS model at the specified material index.

matindex: Material index (1-based in Fortran)
eos: EOS array
gm1: Gamma minus 1 (γ-1)
Cv: Specific heat at constant volume
bb: Covolume parameter
qq: Energy shift parameter
sg_mods_enabled: Optional array for enabling modifiers
sg_mods_values: Optional array for modifier values

Stiff Gas

Note

This model is only available when SINGULARITY_USE_V_AND_V_EOS is ON.

integer function init_sg_StiffGas_f(matindex, eos, gm1, Cv, &
                                   Pinf, qq, &
                                   sg_mods_enabled, sg_mods_values) &
  result(err)
  integer(c_int), value, intent(in) :: matindex
  type(sg_eos_ary_t), intent(in)    :: eos
  real(kind=8), value, intent(in)   :: gm1, Cv, Pinf, qq
  integer(kind=c_int), dimension(:), target, optional, intent(inout) :: sg_mods_enabled
  real(kind=8), dimension(:), target, optional, intent(inout)        :: sg_mods_values
end function init_sg_StiffGas_f

Initializes a Stiff Gas EOS model at the specified material index.

matindex: Material index (1-based in Fortran)
eos: EOS array
gm1: Gamma minus 1 (γ-1)
Cv: Specific heat at constant volume
Pinf: Pressure shift parameter
qq: Energy shift parameter
sg_mods_enabled: Optional array for enabling modifiers
sg_mods_values: Optional array for modifier values

SAP Polynomial

Note

This model is only available when SINGULARITY_USE_V_AND_V_EOS is ON.

integer function init_sg_SAP_Polynomial_f(matindex, eos, rho0, a0, a1, a2c, &
                                         a2e, a3, b0, b1, b2c, b2e, b3, &
                                         sg_mods_enabled, sg_mods_values) &
  result(err)
  integer(c_int), value, intent(in) :: matindex
  type(sg_eos_ary_t), intent(in)    :: eos
  real(kind=8), value, intent(in)   :: rho0, a0, a1, a2c, a2e, a3,&
           b0, b1, b2c, b2e, b3
  integer(kind=c_int), dimension(:), target, optional, intent(inout) :: sg_mods_enabled
  real(kind=8), dimension(:), target, optional, intent(inout)        :: sg_mods_values
end function init_sg_SAP_Polynomial_f

Initializes a SAP Polynomial EOS model at the specified material index. SAP here refers to a specific implementation of a polynomial equation of state.

matindex: Material index (1-based in Fortran)
eos: EOS array
rho0: Reference density
a0, a1, a2c, a2e, a3: Compression polynomial coefficients
b0, b1, b2c, b2e, b3: Expansion polynomial coefficients
sg_mods_enabled: Optional array for enabling modifiers
sg_mods_values: Optional array for modifier values

Additional initialization functions are available when Singularity-EOS is built with specific options:

Helmholtz

Note

Only available when Singularity-eos is built with SINGULARITY_USE_HELMHOLTZ and SINGULARITY_USE_SPINER_WITH_HDF5.

integer function init_sg_Helmholtz_f(matindex, eos, filename, rad, gas, coul, ion, ele, verbose, sg_mods_enabled, sg_mods_values) result(err)
  integer(c_int), value, intent(in) :: matindex
  type(sg_eos_ary_t), intent(in)    :: eos
  character(kind=c_char), dimension(*), intent(in) :: filename
  logical(c_bool), value, intent(in) :: rad, gas, coul, ion, ele, verbose
  integer(kind=c_int), dimension(:), target, optional, intent(inout) :: sg_mods_enabled
  real(kind=8), dimension(:), target, optional, intent(inout)        :: sg_mods_values
end function init_sg_Helmholtz_f

Initializes a Helmholtz equation of state model at the specified material index.

matindex: Material index (1-based in Fortran)
eos: EOS array
filename: Path to the Helmholtz table file (typically “helm_table.dat”)
rad: Boolean to enable/disable radiation term
gas: Boolean to enable/disable gas term
coul: Boolean to enable/disable Coulomb corrections
ion: Boolean to indicate if gas is ionized
ele: Boolean to indicate if electrons are degenerate
verbose: Boolean to enable verbose output
sg_mods_enabled: Optional array for enabling modifiers
sg_mods_values: Optional array for modifier values

Spiner

Note

Only available when Singularity-eos is built with SINGULARITY_USE_SPINER_WITH_HDF5.

integer function init_sg_SpinerDependsRhoT_f(matindex, eos, filename, id, split, sg_mods_enabled, sg_mods_values) result(err)
  integer(c_int), value, intent(in) :: matindex
  type(sg_eos_ary_t), intent(in)    :: eos
  character(kind=c_char), dimension(*), intent(in) :: filename
  integer(c_int), value, intent(in) :: id, split
  integer(kind=c_int), dimension(:), target, optional, intent(inout) :: sg_mods_enabled
  real(kind=8), dimension(:), target, optional, intent(inout)        :: sg_mods_values
end function init_sg_SpinerDependsRhoT_f

Initializes a tabulated EOS model that depends on density (ρ) and temperature (T) using the Spiner interpolation library.

matindex: Material index (1-based in Fortran)
eos: EOS array
filename: Path to the HDF5 file containing the tabulated data
id: Material ID in the HDF5 file
split: Whether or not to separately load electron and ion tables
sg_mods_enabled: Optional array for enabling modifiers
sg_mods_values: Optional array for modifier values

integer function init_sg_SpinerDependsRhoSie_f(matindex, eos, filename, id, split, sg_mods_enabled, sg_mods_values) result(err)
  integer(c_int), value, intent(in) :: matindex
  type(sg_eos_ary_t), intent(in)    :: eos
  character(kind=c_char), dimension(*), intent(in) :: filename
  integer(c_int), value, intent(in) :: id, split
  integer(kind=c_int), dimension(:), target, optional, intent(inout) :: sg_mods_enabled
  real(kind=8), dimension(:), target, optional, intent(inout)        :: sg_mods_values
end function init_sg_SpinerDependsRhoSie_f

Initializes a tabulated EOS model that depends on density (ρ) and specific internal energy (sie) using the Spiner interpolation library.

matindex: Material index (1-based in Fortran)
eos: EOS array
filename: Path to the HDF5 file containing the tabulated data
id: Material ID in the HDF5 file
split: Whether or not to separately load electron and ion tables
sg_mods_enabled: Optional array for enabling modifiers
sg_mods_values: Optional array for modifier values

EOSPAC

Note

Only available when Singularity-eos is built with SINGULARITY_USE_EOSPAC.

integer function init_sg_eospac_f(matindex, eos, id, split, eospac_opts_values, sg_mods_enabled, sg_mods_values) result(err)
  integer(c_int), value, intent(in) :: matindex
  type(sg_eos_ary_t), intent(in)    :: eos
  integer(c_int), value, intent(in) :: id, split
  real(kind=8), dimension(:), target, intent(in) :: eospac_opts_values
  integer(kind=c_int), dimension(:), target, optional, intent(inout) :: sg_mods_enabled
  real(kind=8), dimension(:), target, optional, intent(inout)        :: sg_mods_values
end function init_sg_eospac_f

Initializes an EOSPAC equation of state model at the specified material index.

matindex: Material index (1-based in Fortran)
eos: EOS array
id: SESAME material ID
split: Whether or not to separately load electron and ion tables
eospac_opts_values: Array of EOSPAC-specific options:
- eospac_opts_values(1): invert_at_setup (0/1)
- eospac_opts_values(2): insert_data value
- eospac_opts_values(3): monotonicity option
- eospac_opts_values(4): apply_smoothing (0/1)
- eospac_opts_values(5): apply_splitting option
- eospac_opts_values(6): linear_interp (0/1)
sg_mods_enabled: Optional array for enabling modifiers
sg_mods_values: Optional array for modifier values

EOS Evaluation Functions

The following functions are available for evaluating EOS models:

integer function get_sg_EntropyFromDensityInternalEnergy_f(matindex, &
  eos, rhos, sies, entropies, len, stride, lambda_data) &
  result(err)
  integer(c_int), intent(in) :: matindex, len
  real(kind=8), dimension(:,:,:), intent(in), target:: rhos, sies
  real(kind=8), dimension(:,:,:), intent(inout), target:: entropies
  type(sg_eos_ary_t), intent(in)    :: eos
  integer(c_int), intent(in), optional :: stride
  real(kind=8), dimension(:,:,:,:), intent(inout), target, optional::lambda_data
end function get_sg_EntropyFromDensityInternalEnergy_f

Calculates entropy from density and specific internal energy.

matindex: Material index (1-based in Fortran)
eos: EOS array
rhos: Input density array
sies: Input specific internal energy array
entropies: Output entropy array
len: Number of elements to process
stride: Optional stride for processing elements
lambda_data: Optional array for additional parameters

Warning

Some EOS models do not support Entropy. For more details see models

integer function get_sg_PressureFromDensityInternalEnergy_f(matindex, &
  eos, rhos, sies, pressures, len, stride, lambda_data) &
  result(err)
  integer(c_int), intent(in) :: matindex, len
  real(kind=8), dimension(:,:,:), intent(in), target:: rhos, sies
  real(kind=8), dimension(:,:,:), intent(inout), target:: pressures
  type(sg_eos_ary_t), intent(in)    :: eos
  integer(c_int), intent(in), optional :: stride
  real(kind=8), dimension(:,:,:,:), intent(inout), target, optional::lambda_data
end function get_sg_PressureFromDensityInternalEnergy_f

Calculates pressure from density and specific internal energy.

matindex: Material index (1-based in Fortran)
eos: EOS array
rhos: Input density array
sies: Input specific internal energy array
pressures: Output pressure array
len: Number of elements to process
stride: Optional stride for processing elements
lambda_data: Optional array for additional parameters

integer function get_sg_MinInternalEnergyFromDensity_f(matindex, &
  eos, rhos, sies, len) &
  result(err)
  integer(c_int), intent(in) :: matindex, len
  real(kind=8), dimension(:,:,:), intent(in), target:: rhos
  real(kind=8), dimension(:,:,:), intent(inout), target:: sies
  type(sg_eos_ary_t), intent(in)    :: eos
end function get_sg_MinInternalEnergyFromDensity_f

Calculates minimum internal energy from density.

matindex: Material index (1-based in Fortran)
eos: EOS array
rhos: Input density array
sies: Output minimum specific internal energy array
len: Number of elements to process

integer function get_sg_BulkModulusFromDensityInternalEnergy_f(matindex, &
  eos, rhos, sies, bmods, len, stride, lambda_data) &
  result(err)
  integer(c_int), intent(in) :: matindex, len
  real(kind=8), dimension(:,:,:), intent(in), target:: rhos, sies
  real(kind=8), dimension(:,:,:), intent(inout), target:: bmods
  type(sg_eos_ary_t), intent(in)    :: eos
  integer(c_int), intent(in), optional :: stride
  real(kind=8), dimension(:,:,:,:), intent(inout), target, optional::lambda_data
end function get_sg_BulkModulusFromDensityInternalEnergy_f

Calculates bulk modulus from density and specific internal energy.

matindex: Material index (1-based in Fortran)
eos: EOS array
rhos: Input density array
sies: Input specific internal energy array
bmods: Output bulk modulus array
len: Number of elements to process
stride: Optional stride for processing elements
lambda_data: Optional array for additional parameters

integer function get_sg_eos_f(nmat, ncell, cell_dim,&
                             option,&
                             eos_offsets,&
                             eos,&
                             offsets,&
                             press, pmax, vol, spvol, sie, temp, bmod,&
                             dpde, cv,&
                             frac_mass, frac_vol, frac_sie,&
                             frac_bmod, frac_dpde, frac_cv,&
                             mass_frac_cutoff) &
  result(err)
  integer(kind=c_int), intent(in) :: nmat
  integer(kind=c_int), intent(in) :: ncell
  integer(kind=c_int), intent(in) :: cell_dim
  integer(kind=c_int), intent(in) :: option
  integer(kind=c_int), dimension(:), target, intent(in) :: eos_offsets
  type(sg_eos_ary_t), intent(in)  :: eos
  integer(kind=c_int), dimension(:), target, intent(in) :: offsets
  real(kind=8), dimension(:),   target, intent(in)    :: press
  real(kind=8), dimension(:),   target, intent(in)    :: pmax
  real(kind=8), dimension(:),   target, intent(in)    :: vol
  real(kind=8), dimension(:),   target, intent(in)    :: spvol
  real(kind=8), dimension(:),   target, intent(in)    :: sie
  real(kind=8), dimension(:),   target, intent(in)    :: temp
  real(kind=8), dimension(:),   target, intent(in)    :: bmod
  real(kind=8), dimension(:),   target, intent(in)    :: dpde
  real(kind=8), dimension(:),   target, intent(in)    :: cv
  real(kind=8), dimension(:,:), target, intent(in) :: frac_mass
  real(kind=8), dimension(:,:), target, intent(inout) :: frac_vol
  real(kind=8), dimension(:,:), target, intent(inout) :: frac_sie
  ! optionals
  real(kind=8), dimension(:,:), target, optional, intent(inout) :: frac_bmod
  real(kind=8), dimension(:,:), target, optional, intent(inout) :: frac_dpde
  real(kind=8), dimension(:,:), target, optional, intent(inout) :: frac_cv
  real(kind=8),                         optional, intent(in)    :: mass_frac_cutoff
end function get_sg_eos_f

Main EOS evaluation function for mixed cells. This function is used to calculate various thermodynamic quantities for multiple materials in mixed cells.

nmat: Number of materials
ncell: Number of cells
cell_dim: Cell dimension
option: Option flag for calculation
eos_offsets: Array of EOS offsets
eos: EOS array
offsets: Array of offsets
press: Pressure array
pmax: Maximum pressure array
vol: Volume array
spvol: Specific volume array
sie: Specific internal energy array
temp: Temperature array
bmod: Bulk modulus array
dpde: Derivative of pressure with respect to energy array
cv: Specific heat array
frac_mass: Mass fraction array
frac_vol: Volume fraction array
frac_sie: Specific internal energy fraction array
frac_bmod: Optional bulk modulus fraction array
frac_dpde: Optional derivative of pressure with respect to energy fraction array
frac_cv: Optional specific heat fraction array
mass_frac_cutoff: Optional mass fraction cutoff

Finalization Function

integer function finalize_sg_eos_f(nmat, eos) &
  result(err)
  integer(c_int), value, intent(in) :: nmat
  type(sg_eos_ary_t), intent(in)    :: eos
end function finalize_sg_eos_f

Finalizes the EOS array, freeing any allocated resources.

nmat: Number of materials
eos: EOS array

Examples

Here’s a simple example of using the Fortran interface to initialize and use an Ideal Gas EOS:

program example_sg_fortran_interface
! modules
use singularity_eos_types
use singularity_eos
! no implicit vars
implicit none
! variable declaration
integer                                   :: nmat, res, mat
type(sg_eos_ary_t)                        :: eos
real(kind=8), dimension(1,1,1)            :: rhos, sies, pressures

! set test parameters
nmat = 1

! allocate and initialize eos's
res = init_sg_eos_f(nmat, eos)
mat = 1

! Initialize an ideal gas EOS
res = init_sg_IdealGas_f(mat, eos, 0.4d0, 1.0d7)

! Set input values
rhos(1,1,1) = 1.0d0  ! density in g/cm^3
sies(1,1,1) = 1.0d6  ! specific internal energy in erg/g

! Calculate pressure
res = get_sg_PressureFromDensityInternalEnergy_f(mat, eos, rhos, sies, pressures, 1)

! Print result
print *, "Pressure = ", pressures(1,1,1), " dyne/cm^2"

! cleanup
res = finalize_sg_eos_f(nmat, eos)

end program example_sg_fortran_interface

This example demonstrates using tabulated EOS models with a density-temperature grid:

program tabulated_eos_example
    use singularity_eos_types
    use singularity_eos
    implicit none

    integer :: nmat, res, mat, ncell, cell_dim, option
    type(sg_eos_ary_t) :: eos
    integer :: matid
    integer, allocatable :: eos_offsets(:), offsets(:)
    real(8), allocatable :: press(:), pmax(:), vol(:), spvol(:), sie(:), temp(:)
    real(8), allocatable :: bmod(:), dpde(:), cv(:)
    real(8), allocatable :: density(:)
    real(8), allocatable :: frac_mass(:,:), frac_vol(:,:), frac_sie(:,:)

    ! Grid parameters
    integer :: ndens, ntemp, idx
    real(8) :: dens_min, dens_max, temp_min, temp_max
    real(8), dimension(6) :: eospac_opts
    integer :: i, j

    ! Set up parameters
    nmat = 1
    ndens = 10
    ntemp = 10
    ncell = ndens * ntemp

    ! Define grid ranges
    dens_min = 0.1    ! g/cm^3
    dens_max = 10.0   ! g/cm^3
    temp_min = 0.1    ! eV (note: temperature in eV, not Kelvin)
    temp_max = 100.0  ! eV

    cell_dim = ncell
    option = -3  ! Option flag: -3 means density and temperature as inputs

    ! Allocate arrays
    allocate(eos_offsets(nmat), offsets(ncell), density(ncell))
    allocate(press(ncell), pmax(ncell), vol(ncell), spvol(ncell))
    allocate(sie(ncell), temp(ncell), bmod(ncell), dpde(ncell), cv(ncell))
    allocate(frac_mass(ncell, nmat), frac_vol(ncell, nmat), frac_sie(ncell, nmat))

    ! Initialize arrays
    eos_offsets = 1
    offsets = [(i, i=1,ncell)]
    press = 0.0d0
    pmax = 0.0d0
    vol = 0.0d0
    spvol = 0.0d0
    sie = 0.0d0
    bmod = 0.0d0
    dpde = 0.0d0
    cv = 0.0d0
    frac_mass = 1.0d0
    frac_vol = 1.0d0
    frac_sie = 1.0d0

    ! Set up density-temperature grid
    idx = 0
    do i = 1, ndens
        do j = 1, ntemp
            idx = idx + 1
            ! Logarithmic spacing
            density(idx) = dens_min * (dens_max/dens_min)**((i-1.0d0)/(ndens-1.0d0))
            spvol(idx) = 1.0d0 / density(idx)
            temp(idx) = temp_min * (temp_max/temp_min)**((j-1.0d0)/(ntemp-1.0d0))
        end do
    end do

    ! Initialize EOS
    res = init_sg_eos_f(nmat, eos)
    if (res /= 0) then
        print *, "Error initializing EOS:", res
        stop
    end if

    ! Set EOSPAC options (all zeros for default behavior)
    eospac_opts = 0.0d0

    ! Initialize material with EOSPAC
    mat = 1
    matid = 9999  ! Example material ID
    res = init_sg_eospac_f(mat, eos, matid, eospac_opts)
    if (res /= 0) then
        print *, "Error initializing EOSPAC:", res
        stop
    end if

    ! Calculate EOS properties
    ! Note: Temperature is in eV for get_sg_eos_f
    res = get_sg_eos_f(nmat, ncell, cell_dim, option, &
                      eos_offsets, eos, offsets, &
                      press, pmax, vol, spvol, sie, &
                      temp, bmod, dpde, cv, &
                      frac_mass, frac_vol, frac_sie)
    if (res /= 0) then
        print *, "Error in get_sg_eos_f:", res
        stop
    end if

    ! Print some results
    print *, "Results for first grid point:"
    print *, "Density = ", density(1), " g/cm^3"
    print *, "Temperature = ", temp(1), " eV"
    print *, "Pressure = ", press(1), " dyne/cm^2"
    print *, "SIE = ", sie(1), " erg/g"

    ! Clean up
    deallocate(eos_offsets, offsets, press, pmax, vol, spvol)
    deallocate(sie, temp, bmod, dpde, cv, density)
    deallocate(frac_mass, frac_vol, frac_sie)

    res = finalize_sg_eos_f(nmat, eos)
    if (res /= 0) then
        print *, "Error finalizing EOS:", res
        stop
    end if

end program tabulated_eos_example

Note

When using the get_sg_eos_f function, temperature inputs should be provided in electron volts (eV), not Kelvin. This is different from some other functions in the interface that expect temperature in Kelvin.