Sorry for this simple question, but I never learned nothing about double sums )= , I only know what they are . But finally I had a problem where I need to know something about this, wondering if anyone has material to learn the basics, such as the product of summations, I can write as a double sum and vice versa, learn to turn the indices, etc. Order to gain a little more fluent in basic properties of these sums, and not have to always be deducting things that everybody knows) = Not only with double of multiple sums , also with multiple series, But Only something basic to learn the typical properties )= only this. Thanks!
closed as too broad by Normal Human, Deutsch Mathematiker, tired, Aniket, Cm7F7Bb Nov 6 at 13:33
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