This determines what things can be derived from the supplied
variables. For example, if `salinity`

, `temperature`

,
and `pressure`

are supplied, then potential temperature, sound
speed, and several other things can be derived. If, in addition,
`longitude`

and `latitude`

are supplied, then Absolute Salinity,
Conservative Temperature, and some other things can be derived.
Similarly, `nitrate`

can be computed from `NO2+NO3`

together
with `nitrate`

, and `nitrite`

can be computed from `NO2+NO3`

together with `nitrate`

.
See the “Examples” for a full listing.

## Value

`computableWaterProperties()`

returns a sorted
character vector holding the names of computable
water properties, or NULL, if there are no computable values.

## See also

Other functions that calculate seawater properties:
`T68fromT90()`

,
`T90fromT48()`

,
`T90fromT68()`

,
`locationForGsw()`

,
`swAbsoluteSalinity()`

,
`swAlpha()`

,
`swAlphaOverBeta()`

,
`swBeta()`

,
`swCSTp()`

,
`swConservativeTemperature()`

,
`swDepth()`

,
`swDynamicHeight()`

,
`swLapseRate()`

,
`swN2()`

,
`swPressure()`

,
`swRho()`

,
`swRrho()`

,
`swSCTp()`

,
`swSR()`

,
`swSTrho()`

,
`swSigma()`

,
`swSigma0()`

,
`swSigma1()`

,
`swSigma2()`

,
`swSigma3()`

,
`swSigma4()`

,
`swSigmaT()`

,
`swSigmaTheta()`

,
`swSoundAbsorption()`

,
`swSoundSpeed()`

,
`swSpecificHeat()`

,
`swSpice()`

,
`swSpiciness0()`

,
`swSpiciness1()`

,
`swSpiciness2()`

,
`swSstar()`

,
`swTFreeze()`

,
`swTSrho()`

,
`swThermalConductivity()`

,
`swTheta()`

,
`swViscosity()`

,
`swZ()`

## Examples

```
library(oce)
# Example 1
data(ctd)
computableWaterProperties(ctd)
#> [1] "Absolute Salinity" "CT"
#> [3] "Conservative Temperature" "N2"
#> [5] "Rrho" "RrhoSF"
#> [7] "SA" "SP"
#> [9] "SR" "Sstar"
#> [11] "density" "potential temperature"
#> [13] "sigma0" "sigma1"
#> [15] "sigma2" "sigma3"
#> [17] "sigma4" "sigmaTheta"
#> [19] "sound speed" "spice"
#> [21] "spiciness0" "spiciness1"
#> [23] "spiciness2" "theta"
#> [25] "z"
# Example 2: nothing an be computed from just salinity
computableWaterProperties("salinity")
#> NULL
# Example 3: quite a lot can be computed from this trio of values
computableWaterProperties(c("salinity", "temperature", "pressure"))
#> [1] "N2" "Rrho" "RrhoSF"
#> [4] "SP" "density" "depth"
#> [7] "potential temperature" "sigmaTheta" "sound speed"
#> [10] "spice" "theta" "z"
# Example 4: now we can get TEOS-10 values as well
computableWaterProperties(c(
"salinity", "temperature", "pressure",
"longitude", "latitude"
))
#> [1] "Absolute Salinity" "CT"
#> [3] "Conservative Temperature" "N2"
#> [5] "Rrho" "RrhoSF"
#> [7] "SA" "SP"
#> [9] "SR" "Sstar"
#> [11] "density" "depth"
#> [13] "potential temperature" "sigma0"
#> [15] "sigma1" "sigma2"
#> [17] "sigma3" "sigma4"
#> [19] "sigmaTheta" "sound speed"
#> [21] "spice" "spiciness0"
#> [23] "spiciness1" "spiciness2"
#> [25] "theta" "z"
```