gnuplot: using format data types to seperate a number?

Question

I want to seperate the given range of a logarithmic scale, especially the minimum value. e.g. x_min= 0.2 and I want to get "2" and "-1" as parts of 2*10**(-1) for further usage. From manual, that would be %t and %T. I tried using print ("%T", x_min) but I just get x_min itself, no matter which type I set in print. Is there any way to do this in gnuplot?

You can to use gprintf to do this. But just be aware that there is some inconsistency with gprintf() and %t and %T, as point up by @theozh. — grsousajunior
– grsousajunior, Commented Feb 22, 2020 at 15:47
just saw, print has to be before gprintf. i'll give it a try, thx — Emanrov
– Emanrov, Commented Feb 22, 2020 at 18:32

theozh · Accepted Answer · 2020-02-22 22:06:03Z

2

@GRSousaJR already mentioned some inconsistencies with gprintf() and %t and %T in the comments. I quickly tested with gnuplot 5.2.8, the inconsistencies are still there. A cumbersome solution is given here.

For example:

print gprint("%t",95) gives 0.95 and print gprintf("%T",95) gives 2.

So, 95 = 0.95 x 10^2 is not wrong but the expected result would be 9.5 x 10^1.

But now, if you use for example %.3t instead of %t you will get wrong results. Maybe someone can explain this?!

So in summary: (It's getting a bit lengthy because gprintf() only allows for one parameter.)

Code:

### inconsistency in gprintf with %t and %T
reset session

array Numbers = [0.95, 9.5, 95, 995, 9995]

print "gprintf with %t"
do for [i=1:|Numbers|] {
    print gprintf("% 8g",Numbers[i])." = ".gprintf("%t",Numbers[i])." x 10^".gprintf("%T",Numbers[i])
}
print "gprintf with %.3t"
do for [i=1:|Numbers|] {
    print gprintf("% 8g",Numbers[i])." = ".gprintf("%.3t",Numbers[i])." x 10^".gprintf("%T",Numbers[i])
}
print "gprintf with %.0t"
do for [i=1:|Numbers|] {
    print gprintf("% 8g",Numbers[i])." = ".gprintf("%.0t",Numbers[i])." x 10^".gprintf("%T",Numbers[i])
}
### end of code

Result: (with gnuplot 5.2.8)

gprintf with %t
    0.95 = 9.500000 x 10^-1
     9.5 = 9.500000 x 10^0
      95 = 0.950000 x 10^2    # somehow correct but not the expected result
     995 = 0.995000 x 10^3    # somehow correct but not the expected result
    9995 = 0.999500 x 10^4    # somehow correct but not the expected result
gprintf with %.3t
    0.95 = 9.500 x 10^-1
     9.5 = 9.500 x 10^0
      95 = 9.500 x 10^2    # simply wrong
     995 = 9.950 x 10^3    # simply wrong
    9995 = 9.995 x 10^4    # simply wrong
gprintf with %.0t
    0.95 = 9 x 10^-1
     9.5 = 9 x 10^0
      95 = 1 x 10^2    # somehow ok, rounded. But why not 9 x 10^1, similar to 9.5?
     995 = 1 x 10^3    # ok, rounded
    9995 = 1 x 10^4    # ok, rounded

answered Feb 22, 2020 at 22:06

theozh

27.1k6 gold badges42 silver badges92 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Emanrov Over a year ago

I didn't check but maybe you have to use the same parameter for %T? since this value doesn't change, they easily misfit?

theozh Over a year ago

Do you mean, e.g. %.3T? I don't think so, it wouldn't make too much sense, because power should be an integer number.

Collectives™ on Stack Overflow

gnuplot: using format data types to seperate a number?

1 Answer 1

2 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related