Do not evolve the same Q2 slice more than once

pineappl/src/evolution.rs

@@ -16,7 +16,7 @@ use ndarray::{s, Array1, Array2, Array3, ArrayView1, ArrayView4, Axis};
 use std::iter;
 
 /// Number of ULPS used to de-duplicate grid values in [`Grid::evolve_info`].
-pub(crate) const EVOLVE_INFO_TOL_ULPS: i64 = 64;
+pub(crate) const EVOLVE_INFO_TOL_ULPS: i64 = 256;
 
 /// Number of ULPS used to search for grid values in this module. This value must be a large-enough
 /// multiple of [`EVOLVE_INFO_TOL_ULPS`], because otherwise similar values are not found in

pineappl/src/grid.rs

@@ -1418,6 +1418,15 @@ impl Grid {
 
             op_fac1.push(info.fac1);
 
+            // it's possible that due to small numerical differences we get two slices which are
+            // almost the same. We have to skip those in order not to evolve the 'same' slice twice
+            if used_op_fac1
+                .iter()
+                .any(|&fac| approx_eq!(f64, fac, info.fac1, ulps = EVOLVE_INFO_TOL_ULPS))
+            {
+                continue;
+            }
+
             // skip slices that the grid doesn't use
             if !grid_fac1
                 .iter()
@@ -1543,6 +1552,15 @@ impl Grid {
 
             op_fac1.push(info_a.fac1);
 
+            // it's possible that due to small numerical differences we get two slices which are
+            // almost the same. We have to skip those in order not to evolve the 'same' slice twice
+            if used_op_fac1
+                .iter()
+                .any(|&fac| approx_eq!(f64, fac, info_a.fac1, ulps = EVOLVE_INFO_TOL_ULPS))
+            {
+                continue;
+            }
+
             // skip slices that the grid doesn't use
             if !grid_fac1
                 .iter()