Intersection of two curves in matlab

Hi there i need to calculate intersection point of two curves. Please help i am attaching my code

clc

%crate=0:1:10;

G=-I_BT;

h=4000;%no. of cycles

T=30+273;%temp in kelvin

R=8.314;%universal gas const

capa=200;%battery capacity

%batt_curr batt_HESS=[1,2,3,4]

A=[G];

[n, xout] = hist(A,60);

c_rate=abs((xout.*(n>0))/capa);

B = exp(1.226*exp(-0.2797*c_rate)+9.263);

A_h=abs(xout.*(n>0)).*(n/3600);

Dk=zeros(h,2);

for i=1:h

q_k=B.*exp((-31700+370.3.*c_rate)/(R.*T)).*((i.*A_h).^0.55);

Qk=100-sum(q_k);

Dk(i,:)=Qk;

end

figure(3)

plot(Dk,'LineWidth', 4)

set(gca,'fontsize', 18);

%set(gca,'LineWidth', 4);

ylim([0,100]);

yline(80)

xlabel('No. of Cycles');

ylabel('Capacity Retention %');

%legend('Battery Capacity Retention');

Answer 1

[Torsten]

clc
%crate=0:1:10;
G=-I_BT;
h=4000;%no. of cycles
T=30+273;%temp in kelvin
R=8.314;%universal gas const
capa=200;%battery capacity
%batt_curr batt_HESS=[1,2,3,4]
A=[G];
[n, xout] = hist(A,60);
c_rate=abs((xout.*(n>0))/capa);
B = exp(1.226*exp(-0.2797*c_rate)+9.263);
A_h=abs(xout.*(n>0)).*(n/3600);
fun = @(x) (100 - integral(@(t)B.*exp((-31700+370.3.*c_rate)/(R.*T)).*((t.*A_h).^0.55),0,x)) - 80;
intersection = fzero(fun,3500)

Answer 2

[Star Strider]

The ‘I_BT’ variable is missing, so I cannot run the code. However getting the intersection of the exponential and the line is straightforward —

x = 0:4000;
Dk = 100*exp(-6.5E-5*x);
Cv = 80;

xv = interp1(Dk,x,Cv)

xv = 3.4330e+03

figure
plot(Dk, 'LineWidth',2)
hold on
plot(xv, Cv, 'sr', 'MarkerSize',15, 'LineWidth',2.5)
hold off
xlim([min(x) max(x)])
ylim([0 100])
yline(Cv)

.