adds a test for nearest utilities

devtools/test/chunker_nearestTest.m

@@ -0,0 +1,24 @@
+%chunker.nearest test
+%
+
+iseed = 1234;
+rng(iseed);
+
+% compare closest computed point on circle geometry to exact answer
+
+circ = chunkerfunc(@(t) chnk.curves.bymode(t,1));
+nt = 1000;
+thetas = -pi+2*pi*rand(1,nt);  
+
+% the 0.1 here keeps targets away from coordinate singularity of circle
+scal = 0.1+2*rand(1,nt);
+targs = [cos(thetas); sin(thetas)].*scal;
+
+for j = 1:nt
+    [rn,dn,dist,tn,ichn] = nearest(circ,targs(:,j));
+    th1 = atan2(targs(2,j),targs(1,j));
+    th2 = atan2(rn(2),rn(1));
+    err = min(abs(th1-th2),abs(th1-th2+2*pi));
+    err = min(err,abs(th1-th2-2*pi));
+    assert(err < 1e-12);
+end