R: Second Derivatives of Density wrt Enthalpy

gsw_rho_second_derivatives_wrt_enthalpy {gsw} | R Documentation

## Second Derivatives of Density wrt Enthalpy

### Description

Second Derivatives of Density wrt Enthalpy

### Usage

    gsw_rho_second_derivatives_wrt_enthalpy(SA, CT, p)

### Arguments

`SA` | Absolute Salinity [ g/kg ]
`CT` | Conservative Temperature [ degC ]
`p` | sea pressure [dbar], i.e. absolute pressure [dbar] minus 10.1325 dbar

### Details

The present R function works with a wrapper to a C function contained within the GSW-C system (Version 3.05-4 dated 2017-08-07, available at https://github.com/TEOS-10/GSW-C, as git commit '5b4d959e54031f9e972f3e863f63e67fa4f5bfec'), which stems from the GSW-Fortran system (https://github.com/TEOS-10/GSW-Fortran) which in turn stems from the GSW-Matlab system (https://github.com/TEOS-10/GSW-Matlab). Consult http://www.teos-10.org to learn more about these software systems, their authorships, and the science behind it all.

### Value

A list containing `rho_SA_SA` [ (kg/m^3)/(g/kg)^2 ], the second derivative of density with respect to Absolute Salinity, `rho_SA_h` [ (g/kg)/(g/kg)/(J/kg)], the derivative of density with respect to Absolute Salinity and enthalpy, and `rho_h_h` [ (kg/m^3)/(J/kg)^2 ], the second derivative of density with respect to enthalpy.

### Bugs

As of March 27, 2017, the test values listed in “Examples” do not match values provided at the TEOS-10 website listed in “References”, but they match with values given by the Matlab code that is provided on the TEOS-10 website. It is expected that the TEOS-10 website will be updated by May 2017. As those updates to the TEOS-10 website become available, the present comment will be revised or deleted.

### References

http://www.teos-10.org/pubs/gsw/html/gsw_rho_second_derivatives_wrt_enthalpy.html

### See Also

Other functions with suspicious test values on the TEOS-10 website: `gsw_entropy_second_derivatives`, `gsw_specvol_second_derivatives_wrt_enthalpy`, `gsw_t_freezing_first_derivatives_poly`

### Examples

    SA <- c(34.7118, 34.8915, 35.0256, 34.8472, 34.7366, 34.7324)
    CT <- c(28.8099, 28.4392, 22.7862, 10.2262,  6.8272,  4.3236)
    p <- c(      10,      50,     125,     250,     600,    1000)
    r <- gsw_rho_second_derivatives_wrt_enthalpy(SA, CT, p)
    expect_equal(r$rho_SA_SA/1e-3, c(0.207312267114544, 0.207065033523473, 0.191848346945039,
                                   0.133182862881598, 0.116049034622904, 0.102745309429078))
    expect_equal(r$rho_SA_h/1e-6, c(-0.459053080088382, -0.460370569872258, -0.498605615416296,
                                  -0.642833108550133, -0.682091962941161, -0.706793055445909))
    expect_equal(r$rho_h_h/1e-9, c(-0.454213854637790, -0.455984900239309, -0.499870030989387,
                                 -0.628337767293403, -0.664021595759308, -0.687367088752173))

[Package gsw version 1.0-5 Index]