Yes, ok, it's not a bug. But from a beginners perspective I just wanted

to plot a graph and at least in log mode I had to "set sample <n>" for

the graph to reach the bottom and top axis and be fully drawn. There's

basically no fast way to know that this was necessary.

I don't know but maybe at least some helpful warning should appear when

one uses a certain xy range, specially in log mode (I know it is not

limited to log mode)?

Also of course the log ticks looked ok up to a certain xrange and I had

to use:

"set mxtics 10 # see "help set mxtics"

set mytics 10"

Seems also not beginner friendly or kinda buggy (because it works to a

certain range and then not).

Anyways I just see possible improvements to be made here for a next version.

On 03.08.2016 00:08, Ethan Merritt wrote:

> There is no bug here - you are fighting the limits of floating point

> precision.

> Consider the final steps that are sampled as x approaches 10000.

> For linear sampling in steps of 100

>

> f(9800) is 490000.000000002

> f(9900) is 990000.00000001

> f(10000) is inf (divide by zero at IEEE floating precision)

>

> So f(9900) is the last point that shows on the plot, and that value is

> less

> than the y range you have chosen. The function reaches ymax (10^7) at

> f(9990.)

> To catch that on your plot you must sample finely enough to

> distinguish 9990 from 10000.

>

> And that's for linear sampling. In logscale the sampling must be even

> finer.

> The program selects even samples along the x axis (even spacing on

> log(x)).

> So most of the samples are at low values of x.

>

> On Sun, Jul 31, 2016 at 5:16 AM, D <

[hidden email]
> <mailto:

[hidden email]>> wrote:

>

> Thanks. I had to 'set sample' to 500000 for gnuplot to plot the

> whole line (slightly different xy range and the line goes to the

> bottom). Works in linear mode without the need for any 'set

> sample', wonder why the log mode requires that at all. Maybe you

> should fix that for v5.1 too.

>

>

> On 29.07.2016 20:52, Ethan Merritt wrote:

>> 1) version 5.0:

>> set mxtics 10 # see "help set mxtics"

>> set mytics 10

>>

>> version 5.1

>> currently a bug. thanks for the report

>>

>> 2) set sample 10000

>> Or else define the functions as parametric so that the sample is

>> independent of the x/y precision.

>> But increasing the number of samples is easier.

>>

>> On Fri, Jul 29, 2016 at 11:28 AM, D <

[hidden email]
>> <mailto:

[hidden email]>> wrote:

>>

>> Hi, using:

>>

>> set terminal pngcairo truecolor enhanced font "arial,11"

>> fontscale 1.0

>> size 1000,1000

>> set output "test.png"

>>

>> set log xy

>> #set logscale xy

>>

>> set xrange [100:1e7]

>> set yrange [100:1e7]

>>

>> set grid xtics ytics mxtics mytics lt 0 lw 1 lc rgb "#000000"

>>

>> f(x) = x/ (1-0.0001*x)

>> fi(x) = x/(1/(1-0.0001*x))

>> g(x) = x/ (1-0.0000001*x)

>> gi(x) = x/(1/(1-0.0000001*x))

>> id(x) = x

>>

>> plot f(x) lt 2 lc rgb "#ff0000" lw 1 , \

>> fi(x) lt 2 lc rgb "#ff0000" lw 1 , \

>> g(x) lt 2 lc rgb "#ff0000" lw 1 , \

>> gi(x) lt 2 lc rgb "#ff0000" lw 1 , \

>> id(x) dashtype 2 lc rgb "#000000" lw 1

>>

>> 1) the grid tick lines look either incorrect or at least not

>> to what

>> they look up to [100:1e6]. How can I make them work with

>> [100:1e7] ?

>> 2) the plot of the lines does neither go to the bottom

>> (fi,gi), nor to

>> the top (f,g), as expected. How to fix?

>>

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