# How to use output of NSolve for further calculation and than plot?

I am trying to plot the output using these linear equations but finding some difficulty. Here I am using the output of these linear equations and after that using them in another formula and after that plotting those solutions. But I am not getting any plot. Don't know what is the reason behind this. If anyone can make it possible is most welcome.

wm = 1;
gma = 0.5;
n1 = 0;
G1 = 0.005;
ka = .1;
a1 = 0.7;
a2 = 0.58;
eqns = {V21*wm + V12*wm == 0,
V22*wm + gma*V12 + a1*V13 - G1*a2*V14 - wm*V11 == 0,
V23*wm + G1*a2*V11 - ka*V13 + delc*V14 == 0,
V24*wm + a1*V11 - ka*V14 - delc*V13 == 0,
gma*V21 + G1*a1*V31 - G1*a2*V41 - wm*V11 + wm*V22 == 0,
gma*V22 + a1*V32 - G1*a2*V42 - wm*V12 + gma*V22 + a1*V23 -
G1*a2*V24 - wm*V21 + gma*(2*n1 + 1) == 0,
gma*V23 + a1*V33 - G1*a2*V43 - wm*V13 + G1*a2*V21 - ka*V23 +
delc*V24 == 0,
gma*V24 + a1*V34 - G1*a2*V44 - wm*V14 + a1*V21 - ka*V24 -
delc*V23 == 0, G1*a2*V11 - ka*V31 + delc*V41 + wm*V32 == 0,
G1*a2*V12 - ka*V32 + delc*V42 + gma*V32 + a1*V33 - G1*a2*V34 -
wm*V31 == 0,
G1*a2*V13 - ka*V33 + delc*V43 + G1*a2*V31 - ka*V33 + delc*V34 +
ka/2 == 0,
G1*a2*V14 - ka*V34 + delc*V44 + G1*a1*V31 - ka*V34 - delc*V33 == 0,
G1*a1*V11 - ka*V41 - delc*V31 + wm*V42 == 0,
G1*a1*V12 - ka*V42 - delc*V32 + gma*V42 + G1*a1*V43 - G1*a2*V44 -
wm*V41 == 0,
G1*a1*V13 - ka*V43 - delc*V33 + G1*a2*V41 - ka*V43 + delc*V44 == 0,
G1*a1*V14 - ka*V44 - delc*V34 + G1*a1*V41 - ka*V44 - delc*V43 +
ka/2 == 0};
u = Solve[
eqns, {V11, V12, V13, V14, V21, V22, V23, V24, V31, V32, V33, V34,
V41, V42, V43, V44}];
X1 = ((V11*V22 - V21*V12) + (V33*V44 - V43*V34) + (V13*V24 -
V23*V14)) /. u[[1]];
Y1 = (V14*V23*V32*V41 - V13*V24*V32*V41 - V14*V22*V33*V41 +
V12*V24*V33*V41 + V13*V22*V34*V41 - V12*V23*V34*V41 -
V14*V23*V31*V42 + V13*V24*V31*V42 + V14*V21*V33*V42 -
V11*V24*V33*V42 - V13*V21*V34*V42 + V11*V23*V34*V42 +
V14*V22*V31*V43 - V12*V24*V31*V43 - V14*V21*V32*V43 +
V11*V24*V32*V43 + V12*V21*V34*V43 - V11*V22*V34*V43 -
V13*V22*V31*V44 + V12*V23*V31*V44 + V13*V21*V32*V44 -
V11*V23*V32*V44 - V12*V21*V33*V44 + V11*V22*V33*V44) /. u[[1]];
Z1 = Sqrt[X1^2 - 4*Y1];
Z2 = Sqrt[X1 - Z1]/Sqrt[2];
P3 = Plot[{Evaluate[Max[0, -2*Log2[Z2]]]}, {delc, 0, 4},
Frame -> True,
FrameLabel -> {Style[
"\!$$\*SubscriptBox[\(\[CapitalDelta]$$, $$c$$]\)", Bold, 20],
Style["\!$$\*SubscriptBox[\(E$$, $$N$$]\)", 20]},
FrameTicksStyle -> Directive[FontSize -> 25],
PlotStyle -> {Thickness[0.0005], Thickness[0.004]}]

• see HowTo : Use Rule Solutions in the docs.
– kglr
Apr 5, 2020 at 9:42
– vini
Apr 5, 2020 at 10:40

If you use exact numbers when you define the parameters, that is,

wm = 1;
gma = 1/2;
n1 = 0;
G1 = 5/1000;
ka = 1/10;
a1 = 7/10;
a2 = 58/100;


then

Plot[{Evaluate[Max[0, -2*Log2[Z2]]]}, {delc, 0, 4}, Frame -> True,
FrameLabel -> {Style[ "\!$$\*SubscriptBox[\(Δ$$, $$c$$]\)", Bold, 20],
Style["\!$$\*SubscriptBox[\(E$$, $$N$$]\)", 20]},
FrameTicksStyle -> Directive[FontSize -> 25],
PlotStyle -> {Thickness[0.0005], Thickness[0.004]}]


gives