Log Axes


Log axes can be turned on and off individually for each strip via the special variables Xlogaxis, Ylogaxis, Zlogaxis.


-- log Y axis
Ylogaxis:=on:
Xmin=1; Xmax=100;
Ymin=1; Ymax=100
plot X


-- log X axis
newaxis
Ylogaxis:=off:
Xlogaxis:=on:
plot X



-- log log axis
newaxis
Ydiv:=3:
Ylogaxis:=on:
Xlogaxis:=on:
plot X

-- log Z axis image
Zmin=1; Zmax=1e27
Zlogaxis=on

img[i,j] = i^j dim[20,20]
image img

Xdiv (or Ydiv) can be used to control the number of labeled ticks on the log axis. The concept of distance between ticks doesn't quite apply to a log axis but the basic idea is the same. Higher value divs gives fewer ticks. Ydiv=1 gives all ticks. Ydiv=10 labels only the decades. Ydiv=20 labels every other decade.

Using a Z log axis plots the log of image data. The x,y placement of image data is not affected by X or Y log axes options.

Auto ranging can be used with log axes but it is often best to at least specify the min. If the plot goes to zero or negative there is no information to automatically pick the min.