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
where is an integer. Per default this integer is set to 100. Increase that number to your needs.
Though, the higher the integer is chosen the longer it will take gnuplot to plot the graph.