# Online integrator WolfrAmalpha: 3D vector fields and syntax for double integrals?

1. Apr 13, 2010

### N_F

Online integrator: http://www.wolframalpha.com/

$$\int \int (x,y,z) \times (x,y,z) \times (x,y,z)$$

$$\int_{L1} \int_{L2} (dl1,0,0) \times (dl2,0,0) \times (0,-1,0)$$

What would be correct syntax to evaluate this double integral?

I tried these, but they produce wrong result:

try #1: integral[{l1,0,0} cross {l2,0,0} cross {0,-1,0}, {l1,0,1}, {l2,0,1}]

try #2: integral[l1,0,1] integral[l2,0,1] {l1,0,0} cross {l2,0,0} cross {0,-1,0}

2. Apr 13, 2010

### Lord Crc

Dunno about the vector stuff, but for regular double integrals I've used the following syntax: integrate x^2 * e^y dx dy, x=0..1, y=0..1

edit: however it doesn't seem very smart and in my experience frequently fails even on relatively simple double integrals.

3. Apr 15, 2010

### N_F

That is yet another way to say the same thing, apperantly, but then, I guess, the original result might actually be correct after all. Who is the judge?