2011年3月4日 · I google "latex symbols" when I need something I can't recall. That'll give you many lists and tips. For example, if you choose the first hit, the AoPS list and look for the sum symbol you'll find the product symbol right below it. This is but a simple example of a general technique of exploiting organization and classification on the web to ...

2013年8月27日 · $\sum_{i=m}^n a_i = a_m + a_{m+1} + a_{m+2} +\cdots+ a_{n-1} + a_n.$ Where, i represents the index of summation; a_i is an indexed variable representing each successive term in the series; m is the lower bound of summation, and n is the upper bound of summation. The "i = m" under the summation symbol means that the index i starts out equal to …

2015年6月28日 · The mathematical symbol for the sum of numbers is the summation symbol, represented by the Greek letter sigma (Σ).

For the sake of clarity, I would describe such an operation with the help of a short sentence. Also, it is quite common to put some summation conditions in the index spot of the sum symbol, as in $$\sum_{p \text{ prime}} 1/p$$ In my opinion, it is best to describe what you have written above as

2014年12月20日 · The symbol $\oplus$ means direct sum. You can look at any linear algebra book for definition. Here is one ...

The symbol $\Pi$ is the pi-product. It is like the summation symbol $\sum$ but rather than addition its operation is multiplication. For example, $$ \prod_{i=1}^5i=1\cdot2\cdot3\cdot4\cdot5=120 $$ The other symbol is the coproduct.

Is there any proper mathematical notation that best represents the cumulative sum? $$ y = [x_1, x_1+x_2, x ...

Some mathematicians (perhaps especially set theorists?) might write $\displaystyle \sum S$. This would parallel the way set theorists write $\displaystyle \bigcup S$ where others might write $\displaystyle \bigcup_{x\in S} x$.

Finally, summations of summations are cumbersome to write and extremely difficult to parse in notation-naked writing, but have straightforward notation and interpretation with the $\sum$ symbol. Try writing $$\sum_{a=1}^{100}\sum_{b=1}^a \sum_{c=1}^b \sum_{d=1}^c \big(a-b+c-d\big)$$ without summation notation!

2017年7月4日 · $\begingroup$ The symbol $\oplus$ seems to be used for direct sums in general, not only for orthogonal vector spaces. $\endgroup$ – md2perpe Commented Jul 4, 2017 at 14:55