# How to produce a scatter plot with smooth line for this plot?

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Attached is the capture.png which shows the desired smooth plot that I would like to have. FYP Sample Data.PNG is what I have been getting through the codes below but I need smooth plot just like the one produced in Capture.png.
Can anyone guide how can I produce scatter plot with smooth lines please similar to the Capture.PNG?
Appreciate if anyone can help me. God Bless You!
K = data(1,[1 3 5]) ; % factors
data(1,:) = [];
s1 = data(:,1) ; f1 = data(:,2) ;
s2 = data(:,3) ; f2 = data(:,4) ;
s3 = data(:,5) ; f3 = data(:,6) ;
figure
yyaxis right
plot(s3,f3,'g-o',s2,f2,'b-+')
axis ([0 5 0 90])
ylabel('Force (N)');
yyaxis left
plot(s1,f1,'r-*')
axis ([0 5 0 13])
grid on
title('Force vs Displacement');
xlabel('Displacement (mm)');
ylabel('Force (N)');

Those smooth lines are interpolations between the given points. For you to have a similar result, what you need to do is find an interpolation that is suitable for your expectations about the data and then simply interpolate before plotting. An simple example can be seen below, where the difference between a linear (default) and cubic interpolation can be seen check interp1:
x = 1:10;
y = (-1).^(x);
xq = 1:0.01:10;
yq = interp1(x,y,xq,'PCHIP') ;
figure,plot(x,y,'g-o','linewidth',2)
hold on,plot(xq,yq,'linewidth',2),plot(xq(1:100:end),yq(1:100:end),'r+','linewidth',2) #### 1 Comment

I did the following: But I am getting the error below. Can you tell me what is missing or wrong with this code?
K = data(1,[1 3 5]) ; % factors
data(1,:) = [];
s1 = data(:,1) ; f1 = data(:,2) ;
s2 = data(:,3) ; f2 = data(:,4) ;
s3 = data(:,5) ; f3 = data(:,6) ;
ss1= 0:0.25:5;
ff1=interp1(s1,f1,ss1,'PCHIP');
ss2= 0:0.25:5;
ff2=interp2(s2,f2,ss2,'PCHIP');
ss3= 0:0.25:5;
ff3=interp3(s3,f3,ss3,'PCHIP');
figure
yyaxis right
plot(s3,f3,ss3(1:100:end),ff3(1:100:end),'g-o',s2,f2,ss2(1:100:end),ff2(1:100:end),'b-+')
axis ([0 5 0 90])
ylabel('Force (N)');
yyaxis left
plot(s1,f1,ss1(1:100:end),ff1(1:100:end),'r-*')
axis ([0 5 0 13])
grid on
title('Force vs Displacement');
xlabel('Displacement (mm)');
ylabel('Force (N)');
>> Sample2
Error using griddedInterpolant
The coordinates of the input points must be finite values; Inf and NaN are not permitted.
Error in interp1 (line 134)
F = griddedInterpolant(X,V(:,1),method);
Error in Sample2 (line 8)
ff1=interp1(s1,f1,ss1,'PCHIP');