Conditional ploting in Gnuplot using fortran 90

Question

i have a truss bridge that i want to draw using fortran 90 and Gnuplot , but the truss elements should change color if the corresponding array element is bigger or smaller than zero

open(10,file='plot_2D.plt')
write(10,*) 'set title " truss"'
write(10,*) 'set xrange [0:300]'
write(10,*) 'set yrange [0:40]'
write(10,*) 'set xlabel "x [U]"'
write(10,*) 'set ylabel "y [U]"' 
write(10,*) 'set key noautotitle'        
write(10,*) 'plot "1.txt" if (x(1) > 0 ) {with line 7} else { with line lt 3 } '
write(10,*) 'pause -1 "Hit return to continue"'
close(10)

ofcourse i have 1.txt up to 222.txt but i just put one here because it is repetitive process
but i dont get any plot , what is my mistake ?

Ethan · Accepted Answer · 2020-02-07 17:58:55Z

3

It is not clear what exactly you mean by x(1) > 0 since there is no function x() defined. Assuming that x(1) means data value in column 1, then instead of

write(10,*) 'plot "1.txt" if (x(1) > 0 ) {with line 7} else { with line lt 3 } '

the correct syntax is

write(10,*) 'plot "1.txt" using 1:2:($1>0 ? 7 : 3) with lines linecolor variable'

answered Feb 7, 2020 at 17:58

Ethan

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2 Comments

John Alexiou Over a year ago

is 1>0 ? 7 : 3 a conditional ternary operator?

Ethan Over a year ago

Yes, it is a ternary operator.

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