I\'m trying to plot in gnuplot a log-periodic function: cos((log(abs(t-Tc))*PI/log10(lambda) ) + phi) But because of the nature of log(x) near t
If you want to increase the resolution try
set samples <X>
where <X> is an integer. Per default this integer is set to 100. Increase that number to your needs.
<X>
Though, the higher the integer is chosen the longer it will take gnuplot to plot the graph.