Nozzle Design Error: Matrix is singular, close to singular or badly scaled. Results may be inaccurate. RCOND = NaN.
Greetings everyone, I am trying to look into a code found here corydodson/NozzleDesign: Design of supersonic nozzles (github.com). However, I run into an error whenever I run the code which reads "Matrix is singular, close to singular or badly scaled. Results may be inaccurate. RCOND = NaN. " I belive the error comes from this internalnode.m function. x,y are the coordinates, t0 is the temperature and d can be 0 or 1 depending on the user. Anyway I can resolve this? Any help is appreciated!
function [xOut,yOut,uOut,vOut] = internalnode(t0,species,moleFracs,x,y,u,v,d)
h0 = mixprop(‘h’,species,moleFracs,t0);
r = mixprop(‘r’,species,moleFracs)*1000;
L = length(x);
minus = logical([ones(L – 1,1);0]);
plus = logical([0;ones(L – 1,1)]);
xm = x(minus);
xmCalc = xm;
xp = x(plus);
ym = y(minus);
ymCalc = ym;
yp = y(plus);
ypCalc = yp;
um = u(minus);
umCalc = um;
up = u(plus);
upCalc = up;
vm = v(minus);
vmCalc = vm;
vp = v(plus);
vpCalc = vp;
sp = vm;
N = 20;
err = 1e-4;
notConv = true(1,4);
for i = 1:N
ymCalc = (ym + ymCalc)/2;
ypCalc = (yp + ypCalc)/2;
umCalc = (um + umCalc)/2;
upCalc = (up + upCalc)/2;
vmCalc = (vm + vmCalc)/2;
vpCalc = (vp + vpCalc)/2;
uCalc = [umCalc;upCalc(end)];
vCalc = [vmCalc;vpCalc(end)];
vMag = sqrt(uCalc.^2 + vCalc.^2);
h = h0 – vMag.^2/2000;
t = tempfromprop(species,moleFracs,’h’,h);
g = mixprop(‘gamma’,species,moleFracs,t);
a = sqrt(r*g.*t);
am = a(minus);
ap = a(plus);
mu = asind(a./vMag);
mum = mu(minus);
mup = mu(plus);
theta = atand(vCalc./uCalc);
thetam = theta(minus);
thetap = theta(plus);
lm = tand(thetam – mum);
lp = tand(thetap + mup);
q = uCalc.^2 – a.^2;
qm = q(minus);
qp = q(plus);
rm = 2*umCalc.*vmCalc – qm.*lm;
rp = 2*upCalc.*vpCalc – qp.*lp;
sm = d*am.^2.*vmCalc./ymCalc;
switch isempty(sp(ypCalc == 0))
case 1
sp = d*ap.^2.*vpCalc./ypCalc;
otherwise
sp(ypCalc ~= 0) = d*ap(ypCalc ~= 0).^2.*vpCalc(ypCalc ~= 0)./ypCalc(ypCalc ~= 0);
sp(ypCalc == 0) = sm(end);
end
A = zeros(L);
B = zeros(L,1);
for j = 1:L – 1
A(2*(j – 1) + 1:2*j,2*(j – 1) + 1:2*j) = [1,-lp(j);…
1,-lm(j)];
B(2*(j – 1) + 1:2*j) = [yp(j) – lp(j)*xp(j);…
ym(j) – lm(j)*xm(j)];
end
X = AB;
ymCalc = X(1:2:end);
ypCalc = ymCalc;
xmCalc = X(2:2:end);
xpCalc = xmCalc;
for j = 1:L – 1
A(2*(j – 1) + 1:2*j,2*(j – 1) + 1:2*j) = [qp(j),rp(j);…
qm(j),rm(j)];
B(2*(j – 1) + 1:2*j) = [sp(j)*(xpCalc(j) – xp(j)) + qp(j)*up(j) + rp(j)*vp(j);…
sm(j)*(xmCalc(j) – xm(j)) + qm(j)*um(j) + rm(j)*vm(j)];
end
X = AB;
umCalc = X(1:2:end);
upCalc = umCalc;
vmCalc = X(2:2:end);
vpCalc = vmCalc;
switch i ~= 1
case 1
notConv = abs([xmCalc,ymCalc,umCalc,vmCalc]./check0 – 1) > err;
end
check0 = [xmCalc,ymCalc,umCalc,vmCalc];
switch sum(sum(notConv)) == 0
case 1
break
end
switch isnan(xmCalc) | isnan(ymCalc) | isnan(umCalc) | isnan(vmCalc)
case 1
break
end
end
xOut = xmCalc;
yOut = ymCalc;
uOut = umCalc;
vOut = vmCalc;
endGreetings everyone, I am trying to look into a code found here corydodson/NozzleDesign: Design of supersonic nozzles (github.com). However, I run into an error whenever I run the code which reads "Matrix is singular, close to singular or badly scaled. Results may be inaccurate. RCOND = NaN. " I belive the error comes from this internalnode.m function. x,y are the coordinates, t0 is the temperature and d can be 0 or 1 depending on the user. Anyway I can resolve this? Any help is appreciated!
function [xOut,yOut,uOut,vOut] = internalnode(t0,species,moleFracs,x,y,u,v,d)
h0 = mixprop(‘h’,species,moleFracs,t0);
r = mixprop(‘r’,species,moleFracs)*1000;
L = length(x);
minus = logical([ones(L – 1,1);0]);
plus = logical([0;ones(L – 1,1)]);
xm = x(minus);
xmCalc = xm;
xp = x(plus);
ym = y(minus);
ymCalc = ym;
yp = y(plus);
ypCalc = yp;
um = u(minus);
umCalc = um;
up = u(plus);
upCalc = up;
vm = v(minus);
vmCalc = vm;
vp = v(plus);
vpCalc = vp;
sp = vm;
N = 20;
err = 1e-4;
notConv = true(1,4);
for i = 1:N
ymCalc = (ym + ymCalc)/2;
ypCalc = (yp + ypCalc)/2;
umCalc = (um + umCalc)/2;
upCalc = (up + upCalc)/2;
vmCalc = (vm + vmCalc)/2;
vpCalc = (vp + vpCalc)/2;
uCalc = [umCalc;upCalc(end)];
vCalc = [vmCalc;vpCalc(end)];
vMag = sqrt(uCalc.^2 + vCalc.^2);
h = h0 – vMag.^2/2000;
t = tempfromprop(species,moleFracs,’h’,h);
g = mixprop(‘gamma’,species,moleFracs,t);
a = sqrt(r*g.*t);
am = a(minus);
ap = a(plus);
mu = asind(a./vMag);
mum = mu(minus);
mup = mu(plus);
theta = atand(vCalc./uCalc);
thetam = theta(minus);
thetap = theta(plus);
lm = tand(thetam – mum);
lp = tand(thetap + mup);
q = uCalc.^2 – a.^2;
qm = q(minus);
qp = q(plus);
rm = 2*umCalc.*vmCalc – qm.*lm;
rp = 2*upCalc.*vpCalc – qp.*lp;
sm = d*am.^2.*vmCalc./ymCalc;
switch isempty(sp(ypCalc == 0))
case 1
sp = d*ap.^2.*vpCalc./ypCalc;
otherwise
sp(ypCalc ~= 0) = d*ap(ypCalc ~= 0).^2.*vpCalc(ypCalc ~= 0)./ypCalc(ypCalc ~= 0);
sp(ypCalc == 0) = sm(end);
end
A = zeros(L);
B = zeros(L,1);
for j = 1:L – 1
A(2*(j – 1) + 1:2*j,2*(j – 1) + 1:2*j) = [1,-lp(j);…
1,-lm(j)];
B(2*(j – 1) + 1:2*j) = [yp(j) – lp(j)*xp(j);…
ym(j) – lm(j)*xm(j)];
end
X = AB;
ymCalc = X(1:2:end);
ypCalc = ymCalc;
xmCalc = X(2:2:end);
xpCalc = xmCalc;
for j = 1:L – 1
A(2*(j – 1) + 1:2*j,2*(j – 1) + 1:2*j) = [qp(j),rp(j);…
qm(j),rm(j)];
B(2*(j – 1) + 1:2*j) = [sp(j)*(xpCalc(j) – xp(j)) + qp(j)*up(j) + rp(j)*vp(j);…
sm(j)*(xmCalc(j) – xm(j)) + qm(j)*um(j) + rm(j)*vm(j)];
end
X = AB;
umCalc = X(1:2:end);
upCalc = umCalc;
vmCalc = X(2:2:end);
vpCalc = vmCalc;
switch i ~= 1
case 1
notConv = abs([xmCalc,ymCalc,umCalc,vmCalc]./check0 – 1) > err;
end
check0 = [xmCalc,ymCalc,umCalc,vmCalc];
switch sum(sum(notConv)) == 0
case 1
break
end
switch isnan(xmCalc) | isnan(ymCalc) | isnan(umCalc) | isnan(vmCalc)
case 1
break
end
end
xOut = xmCalc;
yOut = ymCalc;
uOut = umCalc;
vOut = vmCalc;
end Greetings everyone, I am trying to look into a code found here corydodson/NozzleDesign: Design of supersonic nozzles (github.com). However, I run into an error whenever I run the code which reads "Matrix is singular, close to singular or badly scaled. Results may be inaccurate. RCOND = NaN. " I belive the error comes from this internalnode.m function. x,y are the coordinates, t0 is the temperature and d can be 0 or 1 depending on the user. Anyway I can resolve this? Any help is appreciated!
function [xOut,yOut,uOut,vOut] = internalnode(t0,species,moleFracs,x,y,u,v,d)
h0 = mixprop(‘h’,species,moleFracs,t0);
r = mixprop(‘r’,species,moleFracs)*1000;
L = length(x);
minus = logical([ones(L – 1,1);0]);
plus = logical([0;ones(L – 1,1)]);
xm = x(minus);
xmCalc = xm;
xp = x(plus);
ym = y(minus);
ymCalc = ym;
yp = y(plus);
ypCalc = yp;
um = u(minus);
umCalc = um;
up = u(plus);
upCalc = up;
vm = v(minus);
vmCalc = vm;
vp = v(plus);
vpCalc = vp;
sp = vm;
N = 20;
err = 1e-4;
notConv = true(1,4);
for i = 1:N
ymCalc = (ym + ymCalc)/2;
ypCalc = (yp + ypCalc)/2;
umCalc = (um + umCalc)/2;
upCalc = (up + upCalc)/2;
vmCalc = (vm + vmCalc)/2;
vpCalc = (vp + vpCalc)/2;
uCalc = [umCalc;upCalc(end)];
vCalc = [vmCalc;vpCalc(end)];
vMag = sqrt(uCalc.^2 + vCalc.^2);
h = h0 – vMag.^2/2000;
t = tempfromprop(species,moleFracs,’h’,h);
g = mixprop(‘gamma’,species,moleFracs,t);
a = sqrt(r*g.*t);
am = a(minus);
ap = a(plus);
mu = asind(a./vMag);
mum = mu(minus);
mup = mu(plus);
theta = atand(vCalc./uCalc);
thetam = theta(minus);
thetap = theta(plus);
lm = tand(thetam – mum);
lp = tand(thetap + mup);
q = uCalc.^2 – a.^2;
qm = q(minus);
qp = q(plus);
rm = 2*umCalc.*vmCalc – qm.*lm;
rp = 2*upCalc.*vpCalc – qp.*lp;
sm = d*am.^2.*vmCalc./ymCalc;
switch isempty(sp(ypCalc == 0))
case 1
sp = d*ap.^2.*vpCalc./ypCalc;
otherwise
sp(ypCalc ~= 0) = d*ap(ypCalc ~= 0).^2.*vpCalc(ypCalc ~= 0)./ypCalc(ypCalc ~= 0);
sp(ypCalc == 0) = sm(end);
end
A = zeros(L);
B = zeros(L,1);
for j = 1:L – 1
A(2*(j – 1) + 1:2*j,2*(j – 1) + 1:2*j) = [1,-lp(j);…
1,-lm(j)];
B(2*(j – 1) + 1:2*j) = [yp(j) – lp(j)*xp(j);…
ym(j) – lm(j)*xm(j)];
end
X = AB;
ymCalc = X(1:2:end);
ypCalc = ymCalc;
xmCalc = X(2:2:end);
xpCalc = xmCalc;
for j = 1:L – 1
A(2*(j – 1) + 1:2*j,2*(j – 1) + 1:2*j) = [qp(j),rp(j);…
qm(j),rm(j)];
B(2*(j – 1) + 1:2*j) = [sp(j)*(xpCalc(j) – xp(j)) + qp(j)*up(j) + rp(j)*vp(j);…
sm(j)*(xmCalc(j) – xm(j)) + qm(j)*um(j) + rm(j)*vm(j)];
end
X = AB;
umCalc = X(1:2:end);
upCalc = umCalc;
vmCalc = X(2:2:end);
vpCalc = vmCalc;
switch i ~= 1
case 1
notConv = abs([xmCalc,ymCalc,umCalc,vmCalc]./check0 – 1) > err;
end
check0 = [xmCalc,ymCalc,umCalc,vmCalc];
switch sum(sum(notConv)) == 0
case 1
break
end
switch isnan(xmCalc) | isnan(ymCalc) | isnan(umCalc) | isnan(vmCalc)
case 1
break
end
end
xOut = xmCalc;
yOut = ymCalc;
uOut = umCalc;
vOut = vmCalc;
end #matlab, #nozzle, #method of characteristics, #singular MATLAB Answers — New Questions
