How to differentiate the data in excel using a variable?

Hello all,

I am trying to do a differentiation of a variable in excel data with respect to an other variable. For example in my case, the data which has a name in Y in excel has to be differentiated with respect to X. and I need each value after differentiation. Can someone please tell me how can i do it. I am attaching the excel data.

[mahmoud abd elrehem]

write "doc differentiate " in command window

[Vishnuvardhan Naidu Tanga]

Hallo @mahmoud abd elrehem

Thank you for your reply. Can you please elarobrate what you mean.

[Jan]

Is importing the data into Matlab a part of the problem? If so, what have you trired so far? If not, why does it matter if the values are commning from an Excel file?

The gradient() command calculates a derivative.

[Vishnuvardhan Naidu Tanga]

hello @Jan

Thanks for your reply. I can import the data into matlab its not the issue. The issue is how can i integrate one coloum with respect to other?

[Jan]

If you have imported the data already, it is useful to post a small example, how they are represented in Matlab.

You asked for a differentiation at first, but now for an integration. While gradient(x,t) does the first, trapz(x,t) does the second.

Answer 1

[Star Strider]

You can use the gradient function to calculate the numerical derivative —

T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1198533/matlab.xlsx')

T1 = 83×14 table
     X1        Y1       X2        Y2       X3        Y3       X4        Y4       X5        Y5       X6        Y6       X7        Y7  
    _____    ______    _____    ______    _____    ______    _____    ______    _____    ______    _____    ______    _____    ______

        0    2.3438        0    1.9952        0    1.7367        0    1.5374        0    1.3791        0    1.2502        0    1.1433
    0.002    2.3397    0.002    1.9926    0.002     1.735    0.002    1.5363    0.002    1.3782    0.002    1.2496    0.002    1.1428
    0.004     2.328    0.004    1.9854    0.004    1.7303    0.004     1.533    0.004    1.3759    0.004    1.2478    0.004    1.1415
    0.006    2.3081    0.006    1.9731    0.006    1.7221    0.006    1.5273    0.006    1.3717    0.006    1.2448    0.006    1.1391
    0.008    2.2805    0.008    1.9559    0.008    1.7107    0.008    1.5194    0.008     1.366    0.008    1.2405    0.008    1.1359
     0.01    2.2459     0.01    1.9342     0.01    1.6963     0.01    1.5093     0.01    1.3587     0.01     1.235     0.01    1.1317
    0.012    2.2047    0.012    1.9083    0.012    1.6789    0.012    1.4971    0.012    1.3498    0.012    1.2284    0.012    1.1266
    0.014    2.1574    0.014    1.8783    0.014    1.6587    0.014    1.4829    0.014    1.3395    0.014    1.2206    0.014    1.1206
    0.016    2.1048    0.016    1.8445    0.016    1.6359    0.016    1.4668    0.016    1.3277    0.016    1.2117    0.016    1.1138
    0.018    2.0475    0.018    1.8074    0.018    1.6106    0.018    1.4489    0.018    1.3146    0.018    1.2018    0.018    1.1061
     0.02     1.986     0.02    1.7672     0.02    1.5831     0.02    1.4292     0.02    1.3001     0.02    1.1909     0.02    1.0976
    0.022     1.921    0.022    1.7243    0.022    1.5535    0.022     1.408    0.022    1.2844    0.022     1.179    0.022    1.0884
    0.024    1.8531    0.024     1.679    0.024    1.5219    0.024    1.3853    0.024    1.2676    0.024    1.1662    0.024    1.0784
    0.026    1.7826    0.026    1.6316    0.026    1.4887    0.026    1.3612    0.026    1.2496    0.026    1.1524    0.026    1.0677
    0.028      1.71    0.028    1.5825    0.028    1.4539    0.028    1.3358    0.028    1.2306    0.028    1.1379    0.028    1.0564
     0.03    1.6376     0.03    1.5319     0.03    1.4178     0.03    1.3094     0.03    1.2107     0.03    1.1226     0.03    1.0444

[~,dx] = gradient(T1{:,1:2:end});
[~,dy] = gradient(T1{:,2:2:end});

dydx = dy ./ dx

dydx = 83×7

-2.0334 -1.2536 -0.8270 -0.5738 -0.4141 -0.3086 -0.2363 -3.9356 -2.4292 -1.6035 -1.1132 -0.8039 -0.5994 -0.4588 -7.9144 -4.8967 -3.2368 -2.2494 -1.6258 -1.2128 -0.9284 -11.8807 -7.3784 -4.8889 -3.4029 -2.4622 -1.8383 -1.4082 -15.5456 -9.7043 -6.4515 -4.5009 -3.2621 -2.4383 -1.8696 -18.9659 -11.9156 -7.9548 -5.5657 -4.0421 -3.0260 -2.3229 -22.1116 -13.9961 -9.3901 -6.5923 -4.7995 -3.5995 -2.7670 -24.9582 -15.9306 -10.7479 -7.5752 -5.5307 -4.1567 -3.2005 -27.4927 -17.7088 -12.0214 -8.5097 -6.2326 -4.6954 -3.6220 -29.7107 -19.3243 -13.2052 -9.3919 -6.9027 -5.2140 -4.0301

figure
for k = 1:size(dydx,2)
    subplot(4,2,k)
    yyaxis left
    plot(T1{:,(2*k-1)}, T1{:,(2*k-1)+1})
    ylim([0 4])
    yyaxis right
    plot(T1{:,(2*k-1)}, dydx(:,k))
    xlim([0 0.2])
    ylim([-40 0])
    grid
    title(sprintf('X%d,Y%d',[1 1]*k))
end
hl = legend('Data','Derivative');
hs42 = subplot(4,2,8);
hs42.Visible = 'off';
hl.Position = hs42.Position;

% figure                                                  % Check First & Last Assignments
% yyaxis left
% plot(T1.X1, T1.Y1,  T1.X7, T1.Y7)
% yyaxis right
% plot(T1.X1,dydx(:,1),  T1.X7,dydx(:,7))
% grid

This appears to me to be correct. Check it to be certain it produces the desired result.

.

[Vishnuvardhan Naidu Tanga]

Thank you @Star Strider. I am getting the desired results.

[Star Strider]

As always, my pleasure!

This was an interesting problem!

.