Added function to set implicit number of particles.

When there is not molecular system the number of particles can
now be specified using tng_implicit_num_particles_set().

2 files changed, 24 insertions, 2 deletions

diff --git a/include/tng_io.h b/include/tng_io.h
index f162bad..d7ebfb1 100644
--- a/include/tng_io.h
+++ b/include/tng_io.h
@@ -953,6 +953,19 @@ tng_function_status DECLSPECDLLEXPORT tng_num_frames_get
                  int64_t *n);
 
 /**
+ * @brief Set the number of particles, in the case no molecular system is used.
+ * @param tng_data is the trajectory of which to get the number of particles.
+ * @param n is the number of particles to use.
+ * @details When creating a molecular system the number of particles are set
+ * automatically. This should only be used when there is no molecular system
+ * specified or if the number of atoms needs to be overridden for some reason.
+ * @return TNG_SUCCESS (0) if succesful.
+ */
+tng_function_status DECLSPECDLLEXPORT tng_implicit_num_particles_set
+                (tng_trajectory_t tng_data,
+                 const int64_t n);
+
+/**
  * @brief Get the current number of particles.
  * @param tng_data is the trajectory from which to get the number of particles.
  * @param n is pointing to a value set to the number of particles.
diff --git a/src/lib/tng_io.c b/src/lib/tng_io.c
index 1bb6073..875e093 100644
--- a/src/lib/tng_io.c
+++ b/src/lib/tng_io.c
@@ -10040,9 +10040,18 @@ tng_function_status DECLSPECDLLEXPORT tng_num_frames_get
     return(TNG_SUCCESS);
 }
 
+tng_function_status DECLSPECDLLEXPORT tng_implicit_num_particles_set
+                (tng_trajectory_t tng_data,
+                 const int64_t n)
+{
+    tng_data->n_molecules = n;
+
+    return(TNG_SUCCESS);
+}
+
 tng_function_status DECLSPECDLLEXPORT tng_num_particles_get
-                    (const tng_trajectory_t tng_data,
-                     int64_t *n)
+                (const tng_trajectory_t tng_data,
+                 int64_t *n)
 {
     tng_function_status stat;