how to get in the function values above zero only and the plot stop at zero and above

I want only to get Ucell0, Ucell1, Ucell2 the value above zero , and i dont want to show in the plot values below zero

------------------------------------------------------------------------------------

global A

R=8.314;

F=96485;

Alfa=0.1668;

n=2;

c1=174512;

c2=5485;

T=343;

T1=353;

T2=363;

k=123;

b=-c2/T;

jL=2000

g=-237.15*10^3

j0=exp(b)*c1;

j=0:1:2000;

c3=R*T;

c4=Alfa*n*F;

c5=log((jL)./(jL-j));

Uact=(c3/c4)*log(j/j0);

Ucon=(c3/c4)*c5

Uohm=j*(0.01/k);

E=(-1*(g)/(n*F))

Ucell0=(E-Uact-Ucon-Uohm);

P0=abs(Ucell0).*(j)

eff=Ucell0./E;

.............................................................%

b1=-c2/T1;

j01=exp(b1)*c1;

c13=R*T1;

c4=Alfa*n*F;

c5=log((jL)./(jL-j));

Uact1=(c13/c4)*log(j/j01);

Ucon1=(c13/c4)*c5

Uohm1=j*(0.01/k);

E1=(-1*(g)/(n*F))

Ucell1=(E-Uact-Ucon-Uohm);

P1=abs(Ucell1).*(j)

eff1=Ucell1./E1

...............................................................%

b2=-c2/T2;

j02=exp(b2)*c1;

c23=R*T2;

c4=Alfa*n*F;

c5=log((jL)./(jL-j));

Uact2=(c23/c4)*log(j/j02);

Ucon2=(c23/c4)*c5;

Uohm2=j.*(0.01/k);

E2=(-1*(g)/(n*F))

Ucell2=(E2-Uact2-Ucon2-Uohm2);

P2=abs(Ucell2).*abs(j);

eff2=Ucell2./E2;

xlabel("j (A/m^2)")

ylabel ("U(V)")

plot(j,Ucell0,j,Ucell1,j,Ucell2)

Answer 1

[Star Strider]

Use a logical index mask —

global A
R=8.314;
F=96485;
Alfa=0.1668;
n=2;
c1=174512;
c2=5485;
T=343;
T1=353;
T2=363;
k=123;
b=-c2/T;
jL=2000

jL = 2000

g=-237.15*10^3

g = -237150

j0=exp(b)*c1;
j=0:1:2000;
c3=R*T;
c4=Alfa*n*F;
c5=log((jL)./(jL-j));
Uact=(c3/c4)*log(j/j0);
Ucon=(c3/c4)*c5

Ucon = 1×2001

0 0.0000 0.0001 0.0001 0.0002 0.0002 0.0003 0.0003 0.0004 0.0004 0.0004 0.0005 0.0005 0.0006 0.0006 0.0007 0.0007 0.0008 0.0008 0.0008 0.0009 0.0009 0.0010 0.0010 0.0011 0.0011 0.0012 0.0012 0.0012 0.0013

Uohm=j*(0.01/k);
E=(-1*(g)/(n*F))

E = 1.2289

Ucell0=(E-Uact-Ucon-Uohm);
P0=abs(Ucell0).*(j)

P0 = 1×2001

NaN 0.8814 1.6397 2.3514 3.0328 3.6915 4.3321 4.9576 5.5702 6.1714 6.7626 7.3445 7.9182 8.4842 9.0432 9.5955 10.1418 10.6822 11.2171 11.7469 12.2717 12.7919 13.3076 13.8190 14.3263 14.8296 15.3292 15.8251 16.3175 16.8064

eff=Ucell0./E;
.............................................................%
b1=-c2/T1;
j01=exp(b1)*c1;
c13=R*T1;
c4=Alfa*n*F;
c5=log((jL)./(jL-j));
Uact1=(c13/c4)*log(j/j01);
Ucon1=(c13/c4)*c5

Ucon1 = 1×2001

0 0.0000 0.0001 0.0001 0.0002 0.0002 0.0003 0.0003 0.0004 0.0004 0.0005 0.0005 0.0005 0.0006 0.0006 0.0007 0.0007 0.0008 0.0008 0.0009 0.0009 0.0010 0.0010 0.0011 0.0011 0.0011 0.0012 0.0012 0.0013 0.0013

Uohm1=j*(0.01/k);
E1=(-1*(g)/(n*F))

E1 = 1.2289

Ucell1=(E-Uact-Ucon-Uohm);
P1=abs(Ucell1).*(j)

P1 = 1×2001

NaN 0.8814 1.6397 2.3514 3.0328 3.6915 4.3321 4.9576 5.5702 6.1714 6.7626 7.3445 7.9182 8.4842 9.0432 9.5955 10.1418 10.6822 11.2171 11.7469 12.2717 12.7919 13.3076 13.8190 14.3263 14.8296 15.3292 15.8251 16.3175 16.8064

eff1=Ucell1./E1

eff1 = 1×2001

Inf 0.7172 0.6671 0.6378 0.6169 0.6008 0.5875 0.5763 0.5666 0.5580 0.5503 0.5433 0.5369 0.5311 0.5256 0.5205 0.5158 0.5113 0.5071 0.5031 0.4993 0.4957 0.4922 0.4889 0.4857 0.4827 0.4797 0.4769 0.4742 0.4716

...............................................................%
b2=-c2/T2;
j02=exp(b2)*c1;
c23=R*T2;
c4=Alfa*n*F;
c5=log((jL)./(jL-j));
Uact2=(c23/c4)*log(j/j02);
Ucon2=(c23/c4)*c5;
Uohm2=j.*(0.01/k);
E2=(-1*(g)/(n*F))

E2 = 1.2289

Ucell2=(E2-Uact2-Ucon2-Uohm2);
P2=abs(Ucell2).*abs(j);
eff2=Ucell2./E2;
xlabel("j (A/m^2)")
ylabel ("U(V)")


m1 = Ucell0 > 0;
m2 = Ucell1 > 0;
m3 = Ucell2 > 0;


plot(j(m1),Ucell0(m1), j(m2),Ucell1(m2), j(m3),Ucell2(m3))

.

[Mariam Almheiri]

Hi its work with me at Ucell0 Ucell1 and Ucell2 , but I have same problem in P0 ,P1,P2 when ploting its show the negative part , so can you help me to be Ucell0,Ucell1,Ucell2 above than zero and substitute in P0,P1,P2 to get all the value above zero and then plot all of them

[Mariam Almheiri]

Hi its work , but I get the same problem when plot P0,P1,P2 even after I change the code , so can you help me to be Ucell0 Ucell1 Ucell2 above than zero , then substitue in P0,P1,and P2 , SO can plot all of them above zero

[Star Strider]

Sure!

Just do the same with the ‘P’ values as with the others —

global A
R=8.314;
F=96485;
Alfa=0.1668;
n=2;
c1=174512;
c2=5485;
T=343;
T1=353;
T2=363;
k=123;
b=-c2/T;
jL=2000

jL = 2000

g=-237.15*10^3

g = -237150

j0=exp(b)*c1;
j=0:1:2000;
c3=R*T;
c4=Alfa*n*F;
c5=log((jL)./(jL-j));
Uact=(c3/c4)*log(j/j0);
Ucon=(c3/c4)*c5

Ucon = 1×2001

0 0.0000 0.0001 0.0001 0.0002 0.0002 0.0003 0.0003 0.0004 0.0004 0.0004 0.0005 0.0005 0.0006 0.0006 0.0007 0.0007 0.0008 0.0008 0.0008 0.0009 0.0009 0.0010 0.0010 0.0011 0.0011 0.0012 0.0012 0.0012 0.0013

Uohm=j*(0.01/k);
E=(-1*(g)/(n*F))

E = 1.2289

Ucell0=(E-Uact-Ucon-Uohm);
P0=abs(Ucell0).*(j)

P0 = 1×2001

NaN 0.8814 1.6397 2.3514 3.0328 3.6915 4.3321 4.9576 5.5702 6.1714 6.7626 7.3445 7.9182 8.4842 9.0432 9.5955 10.1418 10.6822 11.2171 11.7469 12.2717 12.7919 13.3076 13.8190 14.3263 14.8296 15.3292 15.8251 16.3175 16.8064

eff=Ucell0./E;
.............................................................%
b1=-c2/T1;
j01=exp(b1)*c1;
c13=R*T1;
c4=Alfa*n*F;
c5=log((jL)./(jL-j));
Uact1=(c13/c4)*log(j/j01);
Ucon1=(c13/c4)*c5

Ucon1 = 1×2001

0 0.0000 0.0001 0.0001 0.0002 0.0002 0.0003 0.0003 0.0004 0.0004 0.0005 0.0005 0.0005 0.0006 0.0006 0.0007 0.0007 0.0008 0.0008 0.0009 0.0009 0.0010 0.0010 0.0011 0.0011 0.0011 0.0012 0.0012 0.0013 0.0013

Uohm1=j*(0.01/k);
E1=(-1*(g)/(n*F))

E1 = 1.2289

Ucell1=(E-Uact-Ucon-Uohm);
P1=abs(Ucell1).*(j)

P1 = 1×2001

NaN 0.8814 1.6397 2.3514 3.0328 3.6915 4.3321 4.9576 5.5702 6.1714 6.7626 7.3445 7.9182 8.4842 9.0432 9.5955 10.1418 10.6822 11.2171 11.7469 12.2717 12.7919 13.3076 13.8190 14.3263 14.8296 15.3292 15.8251 16.3175 16.8064

eff1=Ucell1./E1

eff1 = 1×2001

Inf 0.7172 0.6671 0.6378 0.6169 0.6008 0.5875 0.5763 0.5666 0.5580 0.5503 0.5433 0.5369 0.5311 0.5256 0.5205 0.5158 0.5113 0.5071 0.5031 0.4993 0.4957 0.4922 0.4889 0.4857 0.4827 0.4797 0.4769 0.4742 0.4716

...............................................................%
b2=-c2/T2;
j02=exp(b2)*c1;
c23=R*T2;
c4=Alfa*n*F;
c5=log((jL)./(jL-j));
Uact2=(c23/c4)*log(j/j02);
Ucon2=(c23/c4)*c5;
Uohm2=j.*(0.01/k);
E2=(-1*(g)/(n*F))

E2 = 1.2289

Ucell2=(E2-Uact2-Ucon2-Uohm2);
P2=abs(Ucell2).*abs(j);
eff2=Ucell2./E2;
xlabel("j (A/m^2)")
ylabel ("U(V)")

m1 = Ucell0 > 0;
m2 = Ucell1 > 0;
m3 = Ucell2 > 0;

figure
plot(j(m1),Ucell0(m1), j(m2),Ucell1(m2), j(m3),Ucell2(m3))
xlabel("j (A/m^2)")
ylabel ("U(V)")

Pm1 = P0 > 0;
Pm2 = P1 > 0;
Pm3 = P2 > 0;

figure
plot(j(Pm1),P0(Pm1), j(Pm2),P1(Pm2), j(Pm3),P2(Pm3))
xlabel("j (A/m^2)")
ylabel ("P(V)")

.

[Mariam Almheiri]

Thank you very much , its work with all of them !!!

[Star Strider]

As always, my pleasure!