|void yfgrid(lnstyle, nxdiv)||GRIDOPTS.C||Level 1|
|char lnstyle|| = 0 for no y axis subdivisions.
= -1 for tick marks only.
= 1–9 selects the line style used by dashf().
|int nydiv||The number of desired ticks between main grid lines on the y axis. For example, nxdiv = 9 will create 10 subdivisions.|
|yfgrid() is like fgrid() except that grid lines are only drawn parallel to the x axis, intersecting the y axis. xfrgid() draws lines in the other direction.|