complicated system of 3 equations,3 unknowns
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I'm trying to solve a big system of 3 equations 3 unknowns, but i keep getting 0 for all three variables which i'm certain is wrong. I was wondering if im doing something wrong.alph1 alph2 alph3 are my equations and A1 A3 A5 are unknown. Please help me
syms A1 A3 A5 b cr ct
clc
AR=8;
lamda=0.4;
an=2*pi;
zerolift=deg2rad(-1.5);
angleofa=deg2rad(7.6);
teta=[pi/6,pi/3,pi/2];
lamda=0.4;
ct=lamda*cr;
eqn=(b^2)/((cr+ct)*(b/2))==AR;
b=solve(eqn,b);
y1=(-b/2)*cos(teta(1));
y2=(-b/2)*cos(teta(2));
y3=(-b/2)*cos(teta(3));
c1=-cr*((3*3^(1/2))/10 - 1);
c2=cr*(1+(1-lamda)*((2*y2)/b));
c3=cr*(1+(1-lamda)*((2*y3)/b));
n=1
alph1=((2*b)/(pi*c1))*((A1*sin(teta(n)))+(A3*sin(3*teta(n)))+(A5*sin(5*teta(n))))+zerolift+((1*A1*(sin(1*teta(n))/sin(teta(n))))+(3*A3*(sin(3*teta(n))/sin(teta(n))))+(5*A5*(sin(5*teta(n))/sin(teta(n)))));
n=2
alph2=((2*b)/(pi*c2))*((A1*sin(teta(n)))+(A3*sin(3*teta(n)))+(A5*sin(5*teta(n))))+zerolift+((1*A1*(sin(1*teta(n))/sin(teta(n))))+(3*A3*(sin(3*teta(n))/sin(teta(n))))+(5*A5*(sin(5*teta(n))/sin(teta(n)))));
n=3
alph3=((2*b)/(pi*c3))*((A1*sin(teta(n)))+(A3*sin(3*teta(n)))+(A5*sin(5*teta(n))))+zerolift+((1*A1*(sin(1*teta(n))/sin(teta(n))))+(3*A3*(sin(3*teta(n))/sin(teta(n))))+(5*A5*(sin(5*teta(n))/sin(teta(n)))));
eqn1=alph1==zerolift;
eqn2=alph2==zerolift;
eqn3=alph3==zerolift;
sol=solve([eqn1,eqn2,eqn3],[A1,A3,A5]);
A1=sol.A1;
A3=sol.A3;
A5=sol.A5;
1 Kommentar
Star Strider
am 5 Dez. 2017
I edited your Question to select your code, and used the [{}Code] button to format it correctly.
Antworten (1)
Roger Stafford
am 5 Dez. 2017
Bearbeitet: Roger Stafford
am 5 Dez. 2017
You have included 'zerolift' in the alpha equations, but in the 'eqn' equations you have also set the expressions to 'zerolift' which cancels it out. Hence, all zeros would be the solution. You should be consistent. Either include it in the alpha's or include it in the equ's, but not both.
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