Problem with fill()/patch() between two lines in R2023a

I have a problem with the fill()/patch() command when plotting experimental data.

I want to plot a sine wave with an atan background, and i want to make a picture in which the filled region is the one between the two waves. However, when i attempt to fill() (or patch()) i get a straigth line going from the first to the last point in the functions i create, and i don't know how to avoid this.

What am i doing wrong?

Here is the code for the plot:

%define the variable
x = 0:0.05:6.28

x = 1×126

0 0.0500 0.1000 0.1500 0.2000 0.2500 0.3000 0.3500 0.4000 0.4500 0.5000 0.5500 0.6000 0.6500 0.7000 0.7500 0.8000 0.8500 0.9000 0.9500 1.0000 1.0500 1.1000 1.1500 1.2000 1.2500 1.3000 1.3500 1.4000 1.4500

x = transpose(x) 

x = 126×1

0 0.0500 0.1000 0.1500 0.2000 0.2500 0.3000 0.3500 0.4000 0.4500

bg = atan(-x)

bg = 126×1

0 -0.0500 -0.0997 -0.1489 -0.1974 -0.2450 -0.2915 -0.3367 -0.3805 -0.4229

linetofill = sin(x)

linetofill = 126×1

0 0.0500 0.0998 0.1494 0.1987 0.2474 0.2955 0.3429 0.3894 0.4350

bg

bg = 126×1

0 -0.0500 -0.0997 -0.1489 -0.1974 -0.2450 -0.2915 -0.3367 -0.3805 -0.4229

%plot raw spectrum
plot(x, linetofill)
hold on
%fill the lines up to the background contribution
fill([x fliplr(x)], [linetofill fliplr(bg)], 'cyan', "FaceAlpha", 0.5) 
hold off

[Stephen23]

Have a think about what FLIPLR does to a column vector.

Answer 1

[Star Strider]

I am not certain what result you want.

For column vectors, use flip (or flipud) and concatenate the vector arguments vertically —

%define the variable
x = 0:0.05:6.28;
x = transpose(x); 

bg = atan(-x);

linetofill = sin(x);
% bg

%plot raw spectrum
plot(x, linetofill)
hold on
%fill the lines up to the background contribution
patch([x; flip(x)], [linetofill; flip(bg)], 'cyan', "FaceAlpha", 0.5) 
hold off

Is this what you want? (The fill function produces the same result. Use the function you are most comfortable wiith.)

.

[Lorenzo Tortora]

Yes, this is what i wanted to do, sorry for my poor wording. It was both a matter of using the wrong flip function and a missing ";" in the square brackets, i.e. i was writing

patch([x flip(x)], [linetofill flip(bg)]

in my code instead of

patch([x; flip(x)], [linetofill; flip(bg)]

Which i believed produced the unwanted results.

Thanks a lot for the help!

[Star Strider]

As always, my pleasure!