Carry out nodal modulation calculations for tidem(). This function is based directly on t_vuf in the T_TIDE Matlab package (Pawlowicz et al., 2002), which inherits from the Fortran code described by Foreman (1978).

tidemVuf(t, j, latitude = NULL)



a single time in POSIXct() format, with timezone "UTC".


integer vector, giving indices of tidal constituents to use.


optional numerical value containing the latitude in degrees North. If not provided, u in the return value will be a vector consisting of repeated 0 value, and f will be a vector of repeated 1 value.


A list containing items named v, u and f as described in the T_TIDE documentation, as well in Pawlowicz et al. (2002) and Foreman (1978).


  • Foreman, M. G. G., 1978. Manual for Tidal Currents Analysis and Prediction. Pacific Marine Science Report. British Columbia, Canada: Institute of Ocean Sciences, Patricia Bay.

  • Pawlowicz, Rich, Bob Beardsley, and Steve Lentz, 2002. Classical tidal harmonic analysis including error estimates in MATLAB using T_TIDE. Computers and Geosciences, 28, 929-937.

See also


Dan Kelley translated this from the t_vuf function of the T_TIDE Matlab package (see Pawlowicz et al. 2002).


## Look up values for the M2 constituent in Halifax Harbour, Canada.
j <- with(tidedata$const, which(name=="M2"))
tidemVuf(t=as.POSIXct("2008-01-22 18:50:24"), j=j, lat=44.63)
#> $v
#> [1] 0.8992719
#> $u
#> [1] 0.002959181
#> $f
#> [1] 0.9689351