## Introduction

Ascii receivers are enabled using the namelist output. Here is a commented example:

&Output
pickdt = 0.01 ! Pickpoint Sampling
pickDtType = 1 ! Pickpoint Type
RFileName = 'receivers.dat' ! Record Points in extra file
/


If pickDtType = 2, the output is generated every N time steps, where N is set by pickdt. If pickDtType = 1, output is generated every pickdt second.

receivers.dat is an ASCII file describing the coordinates of the receivers in the form:

x1 y1 z1
x2 y2 z2
(...)
xn yn zn


The receivers files contain the time-histories of the stress tensor (6 variables) and the particle velocities (3). Currently, there is no way to write only a subset of these variables.

The variable ReceiverOutputInterval (in the section Output of the Parameter File) controls the frequency of flushing receiver time-histories. If not specified, they are written at the end of the simulation.

## Rotational Output

You can additionally choose to write the rotation of the velocity field by setting ReceiverComputeRotation=1 in the parameter file. The rotation of the vector field is defined as $$\text{rot} v = \begin{pmatrix} \partial_2 v_3 - \partial_3 v_2 \\ \partial_3 v_1 - \partial_1 v_3 \\ \partial_1 v_2 - \partial_2 v_1 \\ \end{pmatrix}$$.

git submodule update --init