How does Ichthyop interpolate the hydrodynamic dataset in time ?

Let's say that the hydrodynamics output dataset is archived with a 5 days time step and Ichthyop runs with a 1 hour time step.

Let's call tn a given time index in the hydrodynamic dataset and tnp1 the following one. And let's call Tr a variable from the dataset (either current velocity, temperature, free surface elevation, etc.). Let's call time the time variable of the hydrodynamic dataset, always expressed in seconds elapsed from a given origin.

Ichthyop does a linear interpolation to estimate the value of Tr at any given time between time(tn) and time(tnp1). For t, a given time index such as time(t) >= time(tn) and time(t) < time(tnp1), we have :

Tr(t) = (1 - x) * Tr(tn) + x * Tr(tnp1)

with x = ( time(t) - time(tn) ) / ( time(tnp1) - time(tn) )