Difference between plot(log(x),log(y)) and loglog(x,y)

What's the difference between plot(log(x),log(y)) and loglog(x,y)? When should the first or second one be used?

Answer 1

[Star Strider]

Axis tick numbering. If you do plot(log(x),log(y)), the axis units will be log(x) and log(y). If you do loglog(x,y), the axis units will be x and y, with the axis ticks scaled logarithmically.

x = 1:10;
y = 1:10:100;

figure(1)
plot(log(x), log(y))
grid

figure(2)
loglog(x,y)
grid

Answer 2

[dpb]

The difference will be on the axes -- the first is a linear plot in log(x,y) whereas the second is the log-axis plot of x,y. The shape of the two will be the same, the displayed scale values different. Easiest way to see the difference is to create a set of data and try it.

The only reason to ever use the first is for the very odd time when one would actually care about what the log() values are--not very often an occurrence I'd think; no real application comes to mind at the moment...

Answer 3

[Walter Roberson]

With loglog(), data cursor information is in original units; with log() log(), data cursor information is in log units. Likewise for setting axis limits (which is also what controls zooming). The automatic positioning of ticks is also affected.

I seem to recall there are also effects on transparency and fill (including painting of solid faces) and on shading.

Answer 4

[Vasu Dev]

x = 1:10;

y = 1:10:100;

figure(1)

plot(log(x), log(y))

grid

figure(2)

loglog(x,y)

grid