mjhjmtu

I am trying to fill in the area under the curve of sin(x)/x. Here is my code:

PassOptionsToPackageusenames,dvipsnames,table,x11namesxcolor
documentclass[a4paper, 12pt]article

usepackageamsmath
usepackageamssymb
usepackagepgfplots
usepackagetkz-euclide
pgfplotssetcompat=1.15
usetikzlibraryarrows,shadows,positioning, calc, decorations.markings, hobby, quotes,angles,decorations.pathreplacing,intersections
usepgfplotslibrarypolar,colormaps,fillbetween
usepgflibraryshapes.geometric
usepackagexcolor

begindocument 

beginfigure[ht]

centering

begintikzpicture[scale=1.5,line width=1pt]
beginaxis[
color= black,
xmin=-1, 
xmax=7.9, 
ymin=-1, 
ymax=2, 
axis equal image, 
axis lines=middle, 
font=scriptsize,
xtick distance=1,
ytick distance=1,
%xticklabels=, 
%yticklabels=,
inner axis line style=stealth-stealth,
xlabel = $x$,
ylabel = $f(x)$,
ticks=none,
]

addplot[black, opacity = 0, domain=0:10, name path = 1]0;

addplot[Tan, smooth, domain=0.01:7.5, samples = 300, name path=2, thick] sin(deg(x))/x; 

%addplot[Tan, fill opacity=0.25] fill between [of=1 and 2,soft clip=domain=0:3.1415];

endaxis
endtikzpicture 

captionIntegrating $sin(x)/x$ from $0 le x < infty$.
label1

endfigure

enddocument

I have the code in a larger document, so here is the output:

When I un-comment out the line to fill in the area, this happens:

There is a noticeable vertical gap and the image is pushed to the left. Any idea why this is happening?

The culprit is scale=1.5, which you should pass to the axis, and not to the tikzpicture. I guess you confuse pgfplots otherwise, see this answer. If you wish to have a core-level explanation, I am afraid I cannot provide it, but given this answer one of my first guesses was to change the position of scale, and it seems to work. Notice also that the pgfplots library fillbetween loads intersections, but a slightly advanced version, so you should not load intersections (again). I also removed tkz-euclide and unused libraries (in order to keep the code tidy), but you may resurrect them and the code still works as it should.

PassOptionsToPackageusenames,dvipsnames,table,x11namesxcolor
documentclass[a4paper, 12pt]article
usepackageamsmath
usepackageamssymb
usepackagepgfplots
%usepackagetkz-euclide
pgfplotssetcompat=1.15
usepgfplotslibrary%polar,colormaps,
fillbetween
% usetikzlibraryarrows,shadows,positioning, calc, decorations.markings, hobby, quotes,angles,decorations.pathreplacing
% usepgflibraryshapes.geometric
%usepackagexcolor


begindocument 

beginfigure[ht]

centering

begintikzpicture[line width=1pt]
beginaxis[scale=1.5,
color= black,
xmin=-1, 
xmax=7.9, 
ymin=-1, 
ymax=2, 
axis equal image, 
axis lines=middle, 
font=scriptsize,
xtick distance=1,
ytick distance=1,
%xticklabels=, 
%yticklabels=,
inner axis line style=stealth-stealth,
xlabel = $x$,
ylabel = $f(x)$,
ticks=none,
]
addplot[black, opacity = 0, domain=0:10, name path = 1]0;

addplot[Tan, smooth, domain=0.01:7.5, samples = 300, name path=2, thick] sin(deg(x))/x; 

addplot[Tan, fill opacity=0.25] fill between [of=1 and 2,soft clip=domain=0:3.1415];

endaxis
endtikzpicture 
captionIntegrating $sin(x)/x$ from $0 le x < infty$.
label1
endfigure
enddocument