# Collier interface¶

Recola uses Collier for the evaluation of scalar and tensor integrals. While most of the interface is hidden from the user, the stability mode and the cache system can be tuned.

## Collier stability modes¶

Collier can be run in 3 different modes and set via

 set_collier_mode_rcl(mode) Set the collier mode to mode.

## Collier cache modes¶

Regarding Collier’s cache, we provide the following options:

• local cache mode: each process has its own cache (default)
• global cache mode: caches are shared among several processes (advanced, best performance)

### Local mode¶

The local mode is fully automated and is used by default. For very challenging processes it is possible to reduce the memory consumption by splitting the cache for individual processes into several parts by calling:

 split_collier_cache_rcl set_collier_cache_rcl(npr, n)

### Global mode¶

The global cache mode needs to be activated explicitly

 set_cache_mode_rcl(mode) Sets the cache mode to mode.

Switching between caches needs to be done manually using the following functions:

 set_global_cache_rcl(ncache) Sets the number of active global caches to ncache. switch_global_cache_rcl(cache) Activates the cache with number cache.