Introduce 'geomatic'

1 files changed, 60 insertions, 0 deletions

diff --git a/src/cell.c b/src/cell.c
index 0be76ff3..c53f63b4 100644
--- a/src/cell.c
+++ b/src/cell.c
@@ -938,3 +938,63 @@ void cell_fudge_gslcblas()
         STATUS("%p\n", cblas_sgemm);
 }
 #endif
+
+
+UnitCell *rotate_cell(UnitCell *in, double omega, double phi, double rot)
+{
+	UnitCell *out;
+	double asx, asy, asz;
+	double bsx, bsy, bsz;
+	double csx, csy, csz;
+	double xnew, ynew, znew;
+
+	cell_get_reciprocal(in, &asx, &asy, &asz, &bsx, &bsy,
+	                        &bsz, &csx, &csy, &csz);
+
+	/* Rotate by "omega" about +z (parallel to c* and c unless triclinic) */
+	xnew = asx*cos(omega) + asy*sin(omega);
+	ynew = -asx*sin(omega) + asy*cos(omega);
+	znew = asz;
+	asx = xnew;  asy = ynew;  asz = znew;
+	xnew = bsx*cos(omega) + bsy*sin(omega);
+	ynew = -bsx*sin(omega) + bsy*cos(omega);
+	znew = bsz;
+	bsx = xnew;  bsy = ynew;  bsz = znew;
+	xnew = csx*cos(omega) + csy*sin(omega);
+	ynew = -csx*sin(omega) + csy*cos(omega);
+	znew = csz;
+	csx = xnew;  csy = ynew;  csz = znew;
+
+	/* Rotate by "phi" about +x (not parallel to anything specific) */
+	xnew = asx;
+	ynew = asy*cos(phi) + asz*sin(phi);
+	znew = -asy*sin(phi) + asz*cos(phi);
+	asx = xnew;  asy = ynew;  asz = znew;
+	xnew = bsx;
+	ynew = bsy*cos(phi) + bsz*sin(phi);
+	znew = -bsy*sin(phi) + bsz*cos(phi);
+	bsx = xnew;  bsy = ynew;  bsz = znew;
+	xnew = csx;
+	ynew = csy*cos(phi) + csz*sin(phi);
+	znew = -csy*sin(phi) + csz*cos(phi);
+	csx = xnew;  csy = ynew;  csz = znew;
+
+	/* Rotate by "rot" about the new +z (in-plane rotation) */
+	xnew = asx*cos(rot) + asy*sin(rot);
+	ynew = -asx*sin(rot) + asy*cos(rot);
+	znew = asz;
+	asx = xnew;  asy = ynew;  asz = znew;
+	xnew = bsx*cos(rot) + bsy*sin(rot);
+	ynew = -bsx*sin(rot) + bsy*cos(rot);
+	znew = bsz;
+	bsx = xnew;  bsy = ynew;  bsz = znew;
+	xnew = csx*cos(rot) + csy*sin(rot);
+	ynew = -csx*sin(rot) + csy*cos(rot);
+	znew = csz;
+	csx = xnew;  csy = ynew;  csz = znew;
+
+	out = cell_new_from_cell(in);
+	cell_set_reciprocal(out, asx, asy, asz, bsx, bsy, bsz, csx, csy, csz);
+
+	return out;
+}