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librheolef-dev_5.93-2_i386 **NAME**

**d_dx**__i__ -- derivatives

**SYNOPSIS**

form (const space V, const space& M, "d_dx0");
form (const space V, const space& M, "d_dx1");
form (const space V, const space& M, "d_dx2");

**DESCRIPTION**

Assembly the form associated to a derivative operator from the **V** finite
element space to the **M** one:
/
| d u
b_i(u,q) = | ---- q dx, i = 0,1,2
| d xi
/ Omega
In the axisymetric **rz** case, the form is defined by
/
| d u
b_0(u,q) = | --- q r dr dz
| d r
/ Omega
If the V space is a **P1** (resp. **P2**) finite element space, the M space may
be a **P0** (resp. **P1d**) one.

**EXAMPLE**

The following piece of code build the Laplacian form associated to the
P1 approximation:
geo omega ("square");
space V (omega, "P1");
space M (omega, "P0");
form b (V, M, "d_dx0");

**LIMITATIONS**

Only edge, triangular and tetrahedal finite element meshes are yet
supported.