# symbolic system of equation

조회 수: 1 (최근 30일)
bhop 2020년 1월 9일
답변: M 2020년 1월 9일
Hi,
It is first time studying on symbolic expressions. I face ''error using zeros'' error when I run following code. Is there anyone can help me about this ?
PS. I added equations as image.
syms gamma w u aoa pi dt b rho
gamma=sym(zeros(i,1));
w=sym(zeros(i,1));
l=sym(zeros(i,1));
for i=1:1:5
if i==1
% rhs1(i)=0
% rhs2(i)=-u*aoa
eqn1=gamma(i)+w(i)==0;
eqn2=gamma(i)+w(i)/(2*pi*((b/2)+(u*dt)/2))==-u*aoa;
else
rhs1=0;
rhs2=-u*aoa;
for j=1:1:i-1
rhs1=-w(j)+rhs1;
rhs2=-w(j)/(2*pi*((b/2)+(((2*i-2*j)+1)*u*dt)/2));
eqn1=gamma(i)+w(i)==rhs1;
eqn2=gamma(i)+w(i)/(2*pi*((b/2)+(u*dt)/2))==rhs2;
eqns=[eqn1,eqn2];
sol=vpasolve(eqns,[gamma(i),w(i)]);
sol.gamma;
sol.w;
end
end
end
if i==1
l(i)=2*b*rho*gamma(i)+rho*u*gamma(i);
else
l(i)=2*b*rho*(gamma(i)-gamma(i-1))+rho*u*gamma(i);
end

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### 답변 (1개)

M 2020년 1월 9일
First problems on lines 2 to 4:
gamma=sym(zeros(i,1));
w=sym(zeros(i,1));
l=sym(zeros(i,1));
i is not yet defined.

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