How to plot discrete points in matlab

I am working on a matlab code to plot mass time graph. On x axis time is mentioned and on yaxis mass is mentioned. x and y have discrete values and their values are the followings: x = 0 5 10 15 20 25 30 35 40 45 and y = 0.008 0.007 0.006 0.004 0.003 0.002 0.001 0.001 0.001 0.001 .When i plot is matlab i dont get a continoous curve rather i get a straight line curve as shown below.

https://www.mathworks.com/matlabcentral/answers/uploaded_files/103676/untitled.jpg The graph i obtained when plotted using microsoft excel is as follows

https://www.mathworks.com/matlabcentral/answers/uploaded_files/103677/18.JPG The graph obtained in excel is what i needed...Can we get the same graph as excel in matlab...my source code is attached here with:

    function [] = a()
clc
x=[0 300 600 900 1200 1500 1800 2100 2400 2700];
y=[8 7 6 4 3 2 1 1 1 1];
plot(x,y,'--')
axis([0 3000 0 inf]);
title('Mass-Time Evaporation Analysis graph' )
xlabel('Time of evaporation in seconds')
ylabel('Mass of blood evaporated in kg')

end end

Answer 1

[Altaïr]

Hey @Rahul Krishna H,

By default, MATLAB's plot function generates piecewise linear segments. To create a smoother curve, interpolation between discrete data points can help. MATLAB offers several interpolation methods:

• PCHIP/Cubic: Shape-preserving piecewise cubic (smooth, maintains monotonicity)
• Spline: Cubic spline interpolation (smooth but may overshoot)
• Makima: Modified Akima cubic interpolation (balances smoothness and shape)

Here's an example using PCHIP interpolation to generate a smooth curve alongside the original data:

% Original data (time in seconds, mass in kg)
x = [0, 300, 600, 900, 1200, 1500, 1800, 2100, 2400, 2700];
y = [0.008, 0.007, 0.006, 0.004, 0.003, 0.002, 0.001, 0.001, 0.001, 0.001]; 

% Create fine grid for smooth interpolation
x_fine = linspace(0, 2700, 1000);   % 1000 points between 0-2700 seconds
y_fine = interp1(x, y, x_fine, 'pchip');  % Cubic interpolation

% Plot settings
plot(x_fine, y_fine, 'b-', 'LineWidth', 1.5);  % Smooth blue curve
hold on;
plot(x, y, ':r', 'LineWidth', 1.5);  % Piecewise linear curve
grid on;

% Axis and labels
axis([0, 3000, 0, 0.009]);  % Extend x-axis to 3000 seconds
title('Mass-Time Evaporation Analysis');
xlabel('Time of evaporation (seconds)');
ylabel('Mass of blood evaporated (kg)');
legend('Interpolated Curve', 'Default Curve', 'Location', 'best');
hold off;

●

The interpolation creates 1000 refined points between measurements, generating a continuous curve while preserving the data's original shape.

For more interpolation options, explore the documentation:

doc interp1