Question: Error table between exact and numeric solution

I have a table that includes the numeric and exact solution of a complex PDE.

I want to calculate error between exact and numeric solution. 
Question 1: Which type of error is mostly used for complex solutions? Absolute error or relative error ,ecludian norm error etc.

Question 2: How to calculate absolute error in complex solutions?

 |abs(Exact_Solution)-abs(Numeric_Solution)|

or

|abs(Exact_Solution-Numeric_Solution)|

restart:
interface(rtablesize=19):
Table_1:=Matrix(19,4,{(1, 1) = x, (1, 2) = t, (1, 3) = Exact_Solution, (1, 4) = 
Numeric_Solution, (2, 3) = .58480350959087385609+1.0129093910559867400*I, (2, 4
) = .58480354764257321311+1.0129094569634633407*I, (3, 2) = .2, (3, 3) = .58507\
763625784549559+1.0133841923708911330*I, (3, 4) = .58507767430954485264+1.01338\
42582783677337*I, (4, 2) = .4, (4, 3) = .58590001649935378049+1.014808596732324\
2462*I, (4, 4) = .58590005455105313755+1.0148086626398008469*I, (5, 2) = .6, (5
, 3) = .58727066619506620449+1.0171826316446769860*I, (5, 4) = .587270690527719\
69197+1.0171826737900691093*I, (6, 2) = .8, (6, 3) = .58918956627727806829+1.02\
05062640817160297*I, (6, 4) = .58918959060993155574+1.0205063062271081530*I, (7
, 2) = 1.0, (7, 3) = .59165666981620797589+1.0247794127586756112*I, (7, 4) = .5\
9165677643905044333+1.0247795974348560123*I, (8, 1) = .5, (8, 3) = .59165805893\
555155139+1.0247818187839564608*I, (8, 4) = .59165677643905044333+1.02477959743\
48560123*I, (9, 1) = .5, (9, 2) = .2, (9, 3) = .58919046685310110177+1.02050782\
39247975919*I, (9, 4) = .58918959060993155574+1.0205063062271081530*I, (10, 1)
= .5, (10, 2) = .4, (10, 3) = .58727131671750391922+1.0171837583825905714*I, (
10, 4) = .58727069052771969197+1.0171826737900691093*I, (11, 1) = .5, (11, 2) =
.6, (11, 3) = .58590207620818846348+1.0148121642526747156*I, (11, 4) = .5859000\
5455105313755+1.0148086626398008469*I, (12, 1) = .5, (12, 2) = .8, (12, 3) = .5\
8507958971290229630+1.0133875758542998141*I, (12, 4) = .58507767430954485264+1.\
0133842582783677337*I, (13, 1) = .5, (13, 2) = 1.0, (13, 3) = .5848057178847424\
9287+1.0129132159331652617*I, (13, 4) = .58480354764257321311+1.012909456963463\
3407*I, (14, 1) = 1.0, (14, 3) = .61222010009837745680+1.0603963187852935669*I,
(14, 4) = .61222010009837745677+1.0603963187852935669*I, (15, 1) = 1.0, (15, 2)
= .2, (15, 3) = .60700988526763399480+1.0513719619800970123*I, (15, 4) = .60700\
988526763399480+1.0513719619800970123*I, (16, 1) = 1.0, (16, 2) = .4, (16, 3) =
.60234868471511732616+1.0432985257988700194*I, (16, 4) = .60234868471511732617+
1.0432985257988700194*I, (17, 1) = 1.0, (17, 2) = .6, (17, 3) = .59823621894610\
415849+1.0361755261425513984*I, (17, 4) = .59823621894610415846+1.0361755261425\
513983*I, (18, 1) = 1.0, (18, 2) = .8, (18, 3) = .59467229263079952050+1.030002\
6246900120270*I, (18, 4) = .59467229263079952054+1.0300026246900120270*I, (19,
1) = 1.0, (19, 2) = 1.0, (19, 3) = .59165677643905044330+1.0247795974348560123*
I, (19, 4) = .59165677643905044333+1.0247795974348560123*I},datatype = anything
,storage = rectangular,order = Fortran_order,shape = [])