Calculates the signed volume of a triangle based on a set of XYZCoords. Signed volume means that volumes can take on a negative value depending on whether the surface normal of the triangle is facing towards or away from the origin. When all positive and negative volumes are integrated across the entire mesh, these values cancel out so that the final volume is an approximation of the total volume of the mesh.

`svol_triangle(XYZCoords)`

- XYZCoords
A dataframe with XYZ coordinates of three points in following order: X1,X2,X3,Y1,Y2,Y3,Z1,Z2,Z3

Value for the signed volume of a triangle.

```
svol_triangle(c(X1 = 1, X2 = 2, X3 = 3 , Y1 = 1, Y2 = 2, Y3 = 1, Z1 = 1, Z2 = 1, Z3 = 1))
#> X3
#> -0.3333333
```