what it ij means?

Question

what it ij means?

Answer 1

Don't know what you're trying to ask, exactly.

I can tell you that I.T. stands for Information Technology.

Answer 2

Depends on the context! There are several ways in which this is commonly used.

The most common way you'd see it exactly like that would be to refer to matrix elements. If A is a matrix, we use A with a subscript ij to refer to the (i, j)'th element of A - that is, the element in row i and column j. I'll denote this as A_ij (where _ indicates subscripting) to illustrate some related examples.

A_ij = (i, j)'thelement of A (as discussed)
[A_ij] = matrix formed from the elements of A, where usually the range of i and j is implied or stated;
A_ji = (j, i)'th element - you see this a lot when you're referring to transpositions, since the transpose of A is merely [A_ji].
A_ii = (i, i)'th element - i.e. looking along the diagonal.


You may also see "i, j" as the range of a summation or product. This simply means that the sum or product goes over all values of i and j (the ranges having previously been defined). It would be rare for the comma not to be included. Additional conditions may also be specified, e.g. "i, j; j > 2". Additional conditions are often specified on a separate line or lines.

Another case where you could see something like this would be in tensor algebra. It's a lot more complicated to explain this notation, particularly in regards to which indexes go at the top and which ones at the bottom, so I won't try now - if it is tensor algebra, please re-post as a separate question and specify that it is tensor algebra. In the meantime, just remember that a repeated index on a single tensor means an implied summation (aka Einstein summation) over that index.

Answer 3

ij is the diagraph of the letters i and j. it is ofter described as a ligature.

Click on the URL below for additional information concerning ij.

en.wikipedia.org/wiki/IJ_(letter)

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Answer 4

tought question idk.