void ylog(xformat, xori, xste, xmax, yori, ymax) LOGPLT.C Level 2
char *xformat The format which will be used for the x axis labels. Use %e, %f, or %g
formats ("%-1.0f" for integer labels), enclosed in double quotes.
float xori The value of  x at the left-hand end of the x axis
float xstep The change in  x between each two tick marks on the x axis.
float xmax The value of  x at the right-hand end of the x axis.
float yori The value of  y at the bottom of the y axis.
float ymax The value of  y at the top of the y axis.
ylog() is used to plot data with a logarithmic y axis and linear x axis. It may be called before the datum points are generated if the scales are known in advance. For a self-scaling version of this function, see ylgscle().  yori and ymax need not be even decades but they should have only one significant figure (e.g., 2., .03, 500., ...).