symbolic code with boundary condition

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MINATI 2019-12-29

评论： MINATI 2019-12-29

t = sym('t'); x = sym('x');

a=5;a1=2;xa=0;xb=3;

g = zeros(1,3,'sym');ga = zeros(1,3,'sym');g(1)=a*x+(5/2)*x.^2;

for i=1:3

ga(i) = subs(g(i),x,t);dga = diff(ga(i),t,1);d2ga = diff(dga,t,1);

Ig1 = int(-ga(i)*d2ga + 2*dga,t,0,t);Ig2=int(Ig1,t,0,t);Ig3=int(Ig2,t,0,x);

g(i+1) = a1*Ig3;

% % disp(g(i+1))

end

g = g(1)+g(2)+g(3)+g(4);

G1 = double(subs(g, x, xn));G2 = [a diff(double(subs(g,x,xn)))];

xn=linspace(xa,xb,100);x = xn;

figure(1)

plot(xn,G1,'LineWidth',1.5)

xlabel('\bf\eta'); ylabel('\bfg(\eta)');

hold on

figure(2)

plot(xn,G2,'LineWidth',1.5)

xlabel('\bf\eta'); ylabel('\bfg^''(\eta)');

hold on

%% G1 should start from '1' and G2 from 'a' end with '0' (in Y-axis)

what modification needed?

MINATI PATRA 2019-12-29

It is defined as linspace in the code

MINATI 2019-12-29

G1(0)=0;G2(0)=a;G2(inf)=0;

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