MATLAB: Differentiate and store results in matrix

differential equationsloopsmatrix

I have two matrices. The first matrix is Density and it 311×1. The second matrix is Temperature and it is 311×21. The column in density matrix corresponds to each distinct column in temperature matrix.
So if I want to plot the first line I could just do:
plot(Density, Temperature(:,1))
and second line would just be:
plot(Density, Temperature(:,2))
How can I create a new matrix that takes the derivative of each temperature line (isotherm) with respect to density, and put this in a new matrix, such as diffTemperature?

Best Answer

Try this:
Density = (0:310)';                                         % Create Data

Temperature = sin((0:310)'*(0:20)*2*pi/20);                 % Create Data
dTdD = gradient(Temperature, mean(diff(Density)));          % Equal Spacing
dTdD = gradient(Temperature) ./ gradient(Density);          % Unequal Spacing
figure
plot(Density, Temperature(:,5))
hold on
plot(Density, dTdD(:,5))
hold off
grid
title('Example')
legend('Temperature', 'Derivative')
xlim([0 30])
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