How do I put annotation text pointing towards specific coordinate?
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Below is my code , I have tried to put annotation text pointing towards a coordinate(3.4, 4.8248) using trial and error method . What is the proper way ?
x=[1 2 2.5 3 4 5]
y=[0 5 7 6.5 2 0]
A=3.4;Lagrange(x,y,A)
function yint=Lagrange(x,y,xx)
A=3.4
n=length(x);
s=0
for i=1:n
product=y(i);
for j=1:n
if i~=j
product=product*(xx-x(j))/(x(i)-x(j));
end
end
s=s+product;
end
yint=s;
figure()
plot(x,y)
hold on
scatter(A,yint,"x","b")
scatter(x,y,"o")
title('Lagrange Interpolation'); xlabel('x'); ylabel('f(x)');
c={A yint}
annotation('textarrow',[0.7 0.6],[0.7 0.64],'String',c)
hold off
legend('Interpolated Function','Result Point f(3.4)','Given Data');
hold off
end
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Accepted Answer
Matt J
on 9 Nov 2021
Edited: Matt J
on 10 Nov 2021
x=[1 2 2.5 3 4 5];
y=[0 5 7 6.5 2 0];
A=3.4;Lagrange(x,y,A);
function yint=Lagrange(x,y,xx)
A=3.4;
n=length(x);
s=0;
for i=1:n
product=y(i);
for j=1:n
if i~=j
product=product*(xx-x(j))/(x(i)-x(j));
end
end
s=s+product;
end
yint=s;
figure()
plot(x,y)
hold on
scatter(A,yint,"x","b")
scatter(x,y,"o")
title('Lagrange Interpolation'); xlabel('x'); ylabel('f(x)');
c={A yint};
%%%%%Matt J added
ax=gca;
xl=xlim;
yl=ylim;
xy0=[xl(1),yl(1)];
Dxy=[diff(xl),diff(yl)];
fn=@(xy) (xy(:)'-xy0)./Dxy.*ax.InnerPosition([3,4])+ax.InnerPosition([1,2]);
p=fn([3.4, 4.8248]);
%%%%%%
annotation('textarrow',[0.7 p(1)],[0.7 p(2)],'String',c)
hold off
legend('Interpolated Function','Result Point f(3.4)','Given Data');
hold off
end
2 Comments
More Answers (1)
Sulaymon Eshkabilov
on 9 Nov 2021
Here you can use the values of c to place where you want your annotation to be displayed along with the arrow. E.g.:
...
c={A yint}
annotation('textarrow',[c{1,1}, c{1,1}-0.07*max(x)]/max(x),[c{1,2},c{1,2}-0.07*max(y)]/max(y),'String',c)
...
3 Comments
Matt J
on 9 Nov 2021
Sulaymon Eshkabilov's comment moved here
WIth the proposed solution, you don't need to find the coordinates by a trial and error. It takes up the found values of c. In other words, the annotation placement changes with respect to the calculated values of c.
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