# How to figure out of MCNP code writing?

1. Feb 28, 2013

### ms.shafeie

I have a question about diffrence between ways of defining a certain plate like (3^1/2)x+y+17.3=0 to MCNP code .for example I know we can define it to MCNP with 15 p 3 2 0 6 but I couldn't understand this method 15 10 0 5 8.66 0 10 0 1

2. Mar 1, 2013

### Stephan_doc

Do you use general plane with equation Ax+By+Cz+D=0, how can obtain A=3, B=2, C=0, D=6 ? What 15 mean, perhaps surface number?

3. Mar 5, 2013

### ms.shafeie

it's just an imaginary surface .for example a part of a cube or everything like this.and 15 is number of surface. is the way of obtaining A, B, C, D important.?

4. May 7, 2013

### DEvens

It's a little hard without the context.

The first one

15 p 3 2 0 6

looks like a plane surface, called surface 15, and defined by Ax + By + Cz – D = 0. So this is A=3, B=2, C=0, and D=6. That is, this corresponds to

3A + 2Y - 6 = 0

But the second one

15 10 0 5 8.66 0 10 0 1

seems to be missing something. If it's supposed to be a surface it needs a keyword to indicate the kind of surface. Is there maybe a number and the letters xyzp missing? If it was something like this

20 xyzp 15 10 0 5 8.66 0 10 0 1

that would be a plane, called surface 20, through the following three points.

(15,10,0)
(5, 8.66, 0)
(10,0,1)

Does this help?
Dan