dials.export format=shelx: Increase number of decimal places in .ins …

…file (#2624)

For `dials.export format=shelx` include one more decimal place in CELL and ZERR instructions, to match XPREP output

newsfragments/2624.bugfix

@@ -0,0 +1 @@
+``dials.export`` ``format=shelx``: Increased precision of unit cell parameters and their estimated standard deviations written to ``.ins`` file 

src/dials/util/export_shelx.py

@@ -159,13 +159,13 @@ def _write_ins(experiment_list, best_unit_cell, composition, ins_file):
             f"TITL {sg.type().number()} in {sg.type().lookup_symbol().replace(' ','')}\n"
         )
         f.write(
-            "CELL {:8.5f} {:8.4f} {:8.4f} {:8.4f} {:8.3f} {:8.3f} {:8.3f}\n".format(
+            "CELL {:7.5f} {:9.5f} {:9.5f} {:9.5f} {:8.4f} {:8.4f} {:8.4f}\n".format(
                 wl, *uc.parameters()
             )
         )
         if uc_sd:
             f.write(
-                "ZERR {:8.3f} {:8.4f} {:8.4f} {:8.4f} {:8.3f} {:8.3f} {:8.3f}\n".format(
+                "ZERR {:7.2f} {:9.5f} {:9.5f} {:9.5f} {:8.4f} {:8.4f} {:8.4f}\n".format(
                     sg.order_z(), *uc_sd
                 )
             )

tests/command_line/test_export.py

@@ -538,8 +538,8 @@ def test_shelx_ins(dials_data, tmp_path):
     assert (tmp_path / "dials.ins").is_file()
 
     cell_esds = {
-        "CELL": (5.4815, 8.2158, 12.1457, 90.000, 90.000, 90.000),
-        "ZERR": (0.0005, 0.0007, 0.0011, 0.003, 0.004, 0.004),
+        "CELL": (5.48154, 8.21578, 12.14570, 90.0000, 90.0000, 90.0000),
+        "ZERR": (0.00050, 0.00073, 0.00109, 0.0034, 0.0037, 0.0037),
     }
 
     with (tmp_path / "dials.ins").open() as fh:
@@ -548,7 +548,7 @@ def test_shelx_ins(dials_data, tmp_path):
             instruction = tokens[0]
             if instruction in cell_esds:
                 result = tuple(map(float, tokens[2:8]))
-                assert result == pytest.approx(cell_esds[instruction], abs=0.001)
+                assert result == pytest.approx(cell_esds[instruction], abs=0.0001)
 
 
 def test_shelx_ins_best_unit_cell(dials_data, tmp_path):