[v6.d REVIEW] Loosen abs on complex tests

- Use is-approx, since we're dealing with floating point math
- Clarify how you get 5e0 from abs(3+4i)

Orig: 2e1428a07

S32-num/complex.t

@@ -218,9 +218,11 @@ ok Num(exp i * π) == -1, 'Num(Complex) pays attention to $*TOLERANCE';
     is ( 42.5-72.5i).truncate,  42-72i, '.truncate (+r-i), .5r, .5i';
     is (-42.5-72.5i).truncate, -42-72i, '.truncate (-r-i), .5r, .5i';
 
-    is-deeply abs(3+4i),      5e0,     'abs(3+4i)';
-    is-deeply abs(i),         1e0,     'abs(i)';
-    cmp-ok    abs(1+i), '==', sqrt(2), 'abs(1+i)';
+    # absolute of a complex is like applying the Pythagoras theorem to a
+    # triangle with a re./im. values being sides and the abs being hypotenuse
+    is-approx abs(3+4i), 5e0,     'abs(3+4i)';
+    is-approx abs(i),    1e0,     'abs(i)';
+    is-approx abs(1+i),  sqrt(2), 'abs(1+i)';
 
     subtest 'Real ≅ Complex' => {
         plan 6;