Rotation centre coordinates need to be in metres (not pixels)

2 files changed, 13 insertions, 10 deletions

diff --git a/libcrystfel/src/predict-refine.c b/libcrystfel/src/predict-refine.c
index d5838e06..4a228dc1 100644
--- a/libcrystfel/src/predict-refine.c
+++ b/libcrystfel/src/predict-refine.c
@@ -283,12 +283,12 @@ int fs_ss_gradient_panel(int param, Reflection *refl, UnitCell *cell,
 }
 
 
-/* Returns dfs_refl/dP and fss_refl/dP, where P = any parameter
- * fs_refl is the fast scan position of refl in panel 'p',
+/* Returns the gradient of fs_dev and ss_dev w.r.t. any parameter.
+ * cx,cy,cz are the rotation axis coordinates (only 2 in use at any time)
  * in metres (not pixels) */
 int fs_ss_gradient(int param, Reflection *refl, UnitCell *cell,
                    struct detgeom_panel *p, gsl_matrix *Minv,
-                   double cx, double cy, double cz,
+                   double cxm, double cym, double czm,
                    float *fsg, float *ssg)
 {
 	signed int h, k, l;
@@ -351,7 +351,10 @@ int fs_ss_gradient(int param, Reflection *refl, UnitCell *cell,
 	} else {
 		return fs_ss_gradient_panel(param, refl, cell, p,
 		                            Minv, fs, ss, mu, t,
-		                            cx, cy, cz, fsg, ssg);
+		                            cxm/p->pixel_pitch,
+		                            cym/p->pixel_pitch,
+		                            czm/p->pixel_pitch,
+		                            fsg, ssg);
 	}
 }
 
diff --git a/tests/gradient_check.c b/tests/gradient_check.c
index 7396b8ad..2a8175e1 100644
--- a/tests/gradient_check.c
+++ b/tests/gradient_check.c
@@ -53,9 +53,9 @@ int main(int argc, char *argv[])
 	double step;
 	gsl_matrix **panel_matrices;
 	int didsomething = 0;
-	const double cx = -200.0;
-	const double cy = +100.0;
-	const double cz = -50.0;
+	const double cx = 0.03;  /* Detector is a 7.5 cm side length square */
+	const double cy = 0.02;
+	const double cz = 0.01;
 
 	rps = make_test_image(&n_refls, &image);
 	panel_matrices = make_panel_minvs(image.detgeom);
@@ -71,7 +71,7 @@ int main(int argc, char *argv[])
 	#ifdef ROTATE_PANEL_X
 	struct detgeom_panel *p = &image.detgeom->panels[0];
 	step = deg2rad(0.01);
-	rotate2d(&p->cnz, &p->cny, cz, cy, step);
+	rotate2d(&p->cnz, &p->cny, cz/p->pixel_pitch, cy/p->pixel_pitch, step);
 	rotate2d(&p->fsz, &p->fsy, 0, 0, step);
 	rotate2d(&p->ssz, &p->ssy, 0, 0, step);
 	didsomething = 1;
@@ -80,7 +80,7 @@ int main(int argc, char *argv[])
 	#ifdef ROTATE_PANEL_Y
 	struct detgeom_panel *p = &image.detgeom->panels[0];
 	step = deg2rad(0.01);
-	rotate2d(&p->cnx, &p->cnz, cx, cz, step);
+	rotate2d(&p->cnx, &p->cnz, cx/p->pixel_pitch, cz/p->pixel_pitch, step);
 	rotate2d(&p->fsx, &p->fsz, 0, 0, step);
 	rotate2d(&p->ssx, &p->ssz, 0, 0, step);
 	didsomething = 1;
@@ -89,7 +89,7 @@ int main(int argc, char *argv[])
 	#ifdef ROTATE_PANEL_Z
 	struct detgeom_panel *p = &image.detgeom->panels[0];
 	step = deg2rad(0.01);
-	rotate2d(&p->cnx, &p->cny, cx, cy, step);
+	rotate2d(&p->cnx, &p->cny, cx/p->pixel_pitch, cy/p->pixel_pitch, step);
 	rotate2d(&p->fsx, &p->fsy, 0, 0, step);
 	rotate2d(&p->ssx, &p->ssy, 0, 0, step);
 	didsomething = 1;