Writing a result on an existing table?

I am new to Matlab. I made a variable named datosraw, it is a 18x3 matrix that contains diameter data, voltage data and current data corresponding to each column.

What i want to do next is multiply the first column (diameter) times 3.1416 and store the result in the SAME variable "datosraw" but in column 4 or alternately on a new variable, i don't know how to do that, appreciate your help!

This is my code:

dprom=datosraw(:,1); %diametro promedio

v=datosraw(:,2); %voltaje

i=datosraw(:,3); %corriente

A=dprom*3.1416;

writetable(A,datosraw);

Answer 1

[George]

Are you using matrices or tables? It's not completely clear to me in your post. If it's a matrix you can do the calculation and concatenation in one step.

>> datosraw = [datosraw datosraw(:,1) * pi]

This takes the original value of datosraw and concatenates it with the first column of datosraw * pi, placing that column at the end.

If you're using tables you can just assign the new table variable as the result of a calculation.

    >> T

    T = 

    promedio    voltaje    corriente
    ________    _______    _________

      0.119     0.81428    0.075854 
    0.49836     0.24352     0.05395 
    0.95974     0.92926      0.5308 
    0.34039     0.34998     0.77917 
    0.58527      0.1966     0.93401 
    0.22381     0.25108     0.12991 
    0.75127     0.61604     0.56882 
     0.2551     0.47329     0.46939 
    0.50596     0.35166    0.011902 
    0.69908     0.83083     0.33712 
     0.8909     0.58526     0.16218 
    0.95929     0.54972     0.79428 
    0.54722     0.91719     0.31122 
    0.13862     0.28584     0.52853 
    0.14929      0.7572     0.16565 
    0.25751     0.75373     0.60198 
    0.84072     0.38045     0.26297 
    0.25428     0.56782     0.65408 

    >> T.result = T.promedio * pi

    T = 

    promedio    voltaje    corriente    result 
    ________    _______    _________    _______

      0.119     0.81428    0.075854     0.37384
    0.49836     0.24352     0.05395      1.5657
    0.95974     0.92926      0.5308      3.0151
    0.34039     0.34998     0.77917      1.0694
    0.58527      0.1966     0.93401      1.8387
    0.22381     0.25108     0.12991     0.70313
    0.75127     0.61604     0.56882      2.3602
     0.2551     0.47329     0.46939      0.8014
    0.50596     0.35166    0.011902      1.5895
    0.69908     0.83083     0.33712      2.1962
     0.8909     0.58526     0.16218      2.7989
    0.95929     0.54972     0.79428      3.0137
    0.54722     0.91719     0.31122      1.7191
    0.13862     0.28584     0.52853      0.4355
    0.14929      0.7572     0.16565     0.46902
    0.25751     0.75373     0.60198     0.80899
    0.84072     0.38045     0.26297      2.6412
    0.25428     0.56782     0.65408     0.79885

    >>

[Claudio Nahmad]

Im using tables, sorry about that, and thank you George!