Mathematica code for sigma?

[Freeman]

What is the code in mathematica for sigma?

[Dave]

Sum[] I think. Just google for it or look in the online help.

[Freeman]

How do I put a limit on it?

[Freeman]

I wanna plug in: [math]\sum_{m=2}_{n=2} m\times n[/math]

[bloodhound]

is that sum rite? how can u have two index in one sum. you probably mean a double sum

[Freeman]

Yes! That's it! How do I have one of those!

[bloodhound]

cant help u there. i dont use mathematica. i use maple

[Dave]

Just use a nested sum (i.e. Sum[sum[]])

[Dave]

Btw, LaTeX code for double sums:

 

[math]\sum_{m=2}\sum_{n=2} m\times n[/math]

[Freeman]

Hey, is it possible to have a sigma equation to figure out all possible solutions for a problem? What would the code of that be?

[Cap'n Refsmmat]

How come when I mouse over latex it gives me that "link hand" that you get over links? And why doesn't it do anything if I click on it?

[Freeman]

Because that's the way it works... it's every premade image put on a site with a lot of bandwidth, then sent here. I think that's how it works...

[Cap'n Refsmmat]

I just checked. It's made as soon as you post it, and the pic stored on Blike's website.

[Freeman]

Is there a sigma equation that gives a set as an answer for mathematica???

[Dave]

Come again?

[Freeman]

Okay, allow me to restate it. The sigma code adds the solutions togather fopr the answer, e.g. [math]\sum_{q=0}^n (q+1)^2[/math] if n was 2 the answer is 5. However, is there an equation which makes the answer to this problem a set? So it would be {1,4} rather than 5.

 

If an equation exists, what would it be on mathematica?

[Freeman]

Like, if I were going to have this equation: [math]n=>2, m=>2, p=>1,

 

{p \times n}-{n \times m}[/math]

With a limit to 1000, how would I encode this???

[jordan]

Okay, allow me to restate it. The sigma code adds the solutions togather fopr the answer, e.g. [math]\sum_{q=0}^n (q+1)^2[/math'] if n was 2 the answer is 5.

Sorry to digress from the topic for a minute, but wouldn't the answer be 14, or is it too late for me to be trying this stuff?

[Freeman]

No, the limit is two. There would be two equations starting with 0, so-

(0+1)^2=1

(1+1)^2=4

1+4=5 QED

ITs a little weird...

[jordan]

But if n=2, doesn't that mean continue through until q has been calculated for 2, thus adding 1+4+9?

[Freeman]

No, you calculate it only twice... Not until q=2. I did the same thing when I learned it at first

[Freeman]

So, is it possible to have a set as an answer? What equation would this be?

[Dave]

No, you calculate it only twice... Not until q=2. I did the same thing when I learned it at first

 

No you don't, it's inclusive.

[YT2095]

Dave, in my calculus book, they use a different symbol for Sum of, it looks like a long S of a fancy f without the line through the middle, is this the same as Sigma?

 

that symbol and `d` are the only I`ve read about yet, `d` being "a little bit of"

 

like dx would be a little bit of x and Sdx would be the sum of all the little bits of x

 

 

is Sigma the same as the long S?

[Dave]

In a sense. What you're talking about is the integral symbol - which is hopefully what I'll be covering in my calculus threads fairly soon if I can get around to writing the next one.

 

Imagine you have a curve, then draw equally spaced lines under the curve so that you can approximate the area under the curve by summing the areas of the trapezia that you've just drawn. Now if you decrease the height of the trapezia and take the limit of the series as the height tends to zero, that's your integral.