Add a function to optimize FK tables in the C-API

Author: Radonirinaunimi

examples/cpp/evolve-grid.cpp

@@ -276,8 +276,13 @@ int main() {
     // Print the results
     print_results(dxsec_grid, dxsec_fktable);
 
+    // write the unoptimised FK table into disk
     pineappl_grid_write(fktable, "evolved-grid.pineappl.lz4");
 
+    // optimise the FK table and then write into disk
+    pineappl_fktable* fktable_opt = pineappl_fktable_optimize(fktable, PINEAPPL_FK_ASSUMPTIONS_NF3_SYM);
+    pineappl_grid_write(fktable_opt, "evolved-grid-optimised.pineappl.lz4");
+
     pineappl_grid_delete(grid);
     pineappl_grid_delete(fktable);
 }

pineappl/src/fk_table.rs

@@ -31,6 +31,7 @@ pub struct FkTable {
 /// tables are typically stored at very small `Q2 = Q0`, the PDFs `f(x,Q0)` of heavy quarks are
 /// typically set to zero at this scale or set to the same value as their anti-quark PDF. This is
 /// used to optimize the size of FK tables.
+#[repr(C)]
 #[derive(Debug, Clone, Copy, Eq, PartialEq)]
 pub enum FkAssumptions {
     /// All quark PDFs are non-zero at the FK table scale and completely independent.

pineappl_capi/cbindgen.toml

@@ -38,6 +38,8 @@ rename_variants = "ScreamingSnakeCase"
 "Channels" = "pineappl_channels"
 "Conv" = "pineappl_conv"
 "ConvType" = "pineappl_conv_type"
+"FkAssumptions" = "pineappl_fk_assumptions"
+"FkTable" = "pineappl_fktable"
 "Grid" = "pineappl_grid"
 "GridOptFlags" = "pineappl_gof"
 "Interp" = "pineappl_interp"

pineappl_capi/src/lib.rs

@@ -60,6 +60,7 @@ use ndarray::{Array4, CowArray, Ix4};
 use pineappl::boc::{Bin, BinsWithFillLimits, Channel, Kinematics, Order, ScaleFuncForm, Scales};
 use pineappl::convolutions::{Conv, ConvType, ConvolutionCache};
 use pineappl::evolution::{AlphasTable, OperatorSliceInfo};
+use pineappl::fk_table::{FkAssumptions, FkTable};
 use pineappl::grid::{Grid, GridOptFlags};
 use pineappl::interpolation::{Interp as InterpMain, InterpMeth, Map, ReweightMeth};
 use pineappl::packed_array::ravel_multi_index;
@@ -2273,3 +2274,24 @@ pub unsafe extern "C" fn pineappl_grid_evolve(
 
     Box::new(fk_table.unwrap().into_grid())
 }
+
+/// Optimize the size of this FK-table by removing heavy quark flavors assumed to be zero.
+///
+/// # Safety
+///
+/// If `grid` does not point to a valid `Grid` object, for example when `grid` is the null pointer,
+/// this function is not safe to call.
+///
+/// # Panics
+///
+/// This function panics if `grid` is not an FK table-like object.
+#[no_mangle]
+pub unsafe extern "C" fn pineappl_fktable_optimize(
+    grid: *mut Grid,
+    assumptions: FkAssumptions,
+) -> Box<FkTable> {
+    let grid = unsafe { &mut *grid };
+    let mut fktable = FkTable::try_from(grid.clone()).unwrap();
+    fktable.optimize(assumptions);
+    Box::new(fktable)
+}