integral

[Ledang]

Hi LabVIEW engineers,

I have problems to perform integral function between two electrical fields E1(x,y) and E2(x,y) in a closed circle with radius 50mm. The electrical fields values (E1 and E2) are saved in different csv file in X,Y and E columns. Can anyone help me on how to solve the problem or give any links which could solve the problem?

Thank you

Ledang

[Hooovahh]

Which part of your task are you having a problem with?  Using the Read From SpreadSheet File.vi under the File I/O palette you can read a file into an array using the delimeter of comma or tab depending on the file format.  Then it is a matter of using the right math functions, or using the formula node to get the desired output from your inputs.

[Ledang]

Hi,

Thaks for the reply. Since the format in CSV I don't have problem to read it in LabVIEW. I'm having problem to find the right functions to perform the integral of E1*E2. Can you suggest the math function to solve it?

Thank you

Fazlul 

[Hooovahh]

Did you search for integral on the palette?  There are several functions, but I think you want Integral x(t).vi.

[billko]

FYI - searching in the function palette is an excellent way of finding things until you are familiar with the palette.  It's also an excellent way to find a VI by description.  Most VIs are given names that are very descriptive.

[Ledang]

Hi,

Thanks for the suggestion. 

regards

Fazlul

[Ledang]

Hi all,

I'm a bit confusing now on how to perform integral function according to equation in attachment (sensitivity.jpg). Currently I'm trying to obtain a sensitivity map inside a circle (center at (0,0) ) with radius 50mm. The electric field excitation labelled as Ei and the measurement electric field as Ej. The saved files(*.csv) are both the data of Ei(x,y)/Ii and Ej(x,y)/Ij . Each excitation and measurement files are contained with 3 column (X,Y and E) with 413 755 and 207 950 rows respectively. After a while trying I still could not understand how to connect these data into the integral function in LabVIEW to obtain results proposed by the equation in the attachment. Can anyone guide me on how to solve the problem? or is there any examples which is similar to what I am trying to accomplish here.

Regards

Fazlul

[ghighuphu]

Dear Ledang,

excitation.jpg ‏and measurement.jpg ‏shows the same data. Is this on purpose?

Please, explain the column in your screenshots. Is [A, B, C] = [x, y, E_i(x,y)/I_i]?

Cheers,

[ghighuphu]

---

@Hooovahh wrote:

Did you search for integral on the palette?  There are several functions, but I think you want Integral x(t).vi.

---

Dear Ledang, I think you have to use two (1D) integrals in a row. The innner integrates over x and the outter over y.

Or you build your own procedure using elementary sums. If [x, y, E_i] is the structure (see previous post), then the step size is small enough and the changes in E_i are "slow". So, your integral would seem sth like:

sum_y sum_x E(x,y)*E(x,y) dx dy

Additionally, at both suggestions above, you have to check for [x,y] in P(50,50) for each row -- by cutting out the relevant portions of the row according the geometrical distance from [0, 0].

Send some data files, somebody might want to try it hands-on.

[Ledang]

Hi,

Yes the data in the previous screenshot was

column A: x coordinate, B:y coordinate, C: Ei(x,y)/Ii @ Ej(x,y)/Ij

After a while the number of rows which reaches to hundreds thousand is time consuming. I however managed to reduce the data to 64x64 pixels (using bilinear interpolation) which is more reasonable for computational purpose. Now the new dataset is in 2d (64x64). The problem is I still have no idea how to integrate the 2d files (excitation and measurement). Please guide me on this. As requested, I also attached the new dataset (64x64).

Regards

Fazlul