Add a test for tffm0()

1 files changed, 12 insertions, 8 deletions

diff --git a/man/tffm0.Rd b/man/tffm0.Rd
index 46978d5e..89bee7d9 100644
--- a/man/tffm0.Rd
+++ b/man/tffm0.Rd
@@ -22,16 +22,20 @@ A vector of the transformed formation fractions
 A vector of backtransformed formation fractions for natural use in degradation models
 }
 \description{
-The transformed fractions can be restricted between 0 and 1 in model
-optimisations. Therefore this transformation was used originally in mkin. It
-was later replaced by the \link{ilr} transformation because the ilr transformed
+This transformation was used originally in mkin, in order to implement a
+constraint for the sum of formation fractions to be smaller than 1.  It was
+later replaced by the \link{ilr} transformation because the ilr transformed
 fractions can assumed to follow normal distribution. As the ilr
 transformation is not available in \link{RxODE} and can therefore not be used in
-the nlmixr modelling language, this transformation is currently used for
-translating mkin models with formation fractions to more than one target
-compartment for fitting with nlmixr in \link{nlmixr_model}. However,
-this implementation cannot be used there, as it is not accessible
-from RxODE.
+the nlmixr modelling language, the original transformation is currently used
+for translating mkin models with formation fractions to more than one target
+compartment for fitting with nlmixr in \link{nlmixr_model}. However, this
+implementation cannot be used there, as it is not accessible from RxODE.
+}
+\details{
+If the transformed formation fractions are restricted to the interval
+between 0 and 1, the sum of backtransformed values is restricted
+to this interval.
 }
 \examples{
 ff_example <- c(