MATLAB: Vibration of plate and disk

error

Hi
Can anyone help me figure out why I am getting this error? I am using Matlab R2008a 7.6.0.324
??? Error using ==> set
Bad value for axes property: 'ZLim'
Values must be increasing and non-NaN.
Error in ==> axis>LocSetLimits at 215
        set(ax,...
Error in ==> axis at 94
                LocSetLimits(ax(j),cur_arg);
Error in ==> untitled2>membanim at 178
  surf(x,y,u(:,:,j)), axis(range)
Error in ==> untitled2 at 77
membanim(u,x,y,t);
P.S. I am also new to matlab
FULL CODE: [This is an excerpt from the book ADVANCED MATH AND MECHANICS APPLICATIONS USING MATLAB]
    function [u,x,y,t]= membwave(type,dims,alp,w,tmax)
  disp('')
  disp('WAVE MOTION IN A RECTANGULAR OR CIRCULAR')
  disp(' MEMBRANE HAVING AN OSCILLATING LOAD')
  if nargin > 0 % Data passed through the call list
    % must specify: type, dims, alp, w, tmax
    % Typical values are: a=2; b=1; alp=1;
    % w=18.4; x0=1; y0=0.5; tmax=5;
    if type==1
      a=dims(1); b=dims(2); x0=dims(3); y0=dims(4);
      [u,x,y,t]=memrecwv(a,b,alp,w,x0,y0,tmax);
    else
      r0=dims(1);
    end
    else % Interactive data input
  disp(' '), disp('Select the geometry type:')
  type=input(['Enter 1 for a rectangle, ',...      
        '2 for a circle > ? ']);
  if type ==1
    disp(' ')
    disp('Specify the rectangle dimensions:')
    s=input('Give values for a,b > ? ','s');
    s=eval(['[',s,']']); a=s(1); b=s(2);
    disp(' ')
    disp('Give coordinates (x0,y0) where the')
    s=input('force acts. Enter x0,y0 > ? ','s');
    s=eval(['[',s,']']); x0=s(1); y0=s(2);
    disp(' '), alp=input('Enter the wave speed > ? ');
    N=40; M=40; pan=pi/a*(1:N)'; pbm=pi/b*(1:M);
    W=alp*sqrt(repmat(pan.^2,1,M)+repmat(pbm.^2,N,1));
    wsort=sort(W(:)); wsort=reshape(wsort(1:42),6,7)';
    disp(' ')
    disp(['The first forty-two natural ',...   
      'requencies are:'])
    disp(wsort)
    w=input(...
    'Input the frequency of the forcing function ?');
    
  else
    disp(' '), disp(... 
    'The circle radius equals one. Give the radial')
    disp(... 
    'distance r0 from the circle center to the')
    r0=input('force > ? ');
    
    disp(' '), alp=input('Enter the wave speed > ?');
    % First 42 Bessel function roots
    wsort=alp*[... 
      2.4048 3.8317 5.1356 5.5201 6.3801 7.0156
      7.5883 8.4173 8.6537 8.7715 9.7611 9.9362
      10.1735 11.0647 11.0864 11.6199 11.7916 12.2251
      12.3385 13.0152 13.3237 13.3543 13.5893 14.3726
      14.4755 14.7960 14.8213 14.9309 15.5898 15.7002
      16.0378 16.2234 16.4707 16.6983 17.0037 17.2412
      17.6159 17.8014 17.9599 18.0711 18.2876 18.4335];
    disp(' '), disp(['The first forty-two',... 
          'natural frequencies are:'])
    disp(wsort)
    w=input('Input the frequency of the forcing function ? ');
  end
    disp(' ')
    disp('Input the maximum solution evaluation time.')
    tmax=input(' > ? ');
  end
if type==1
  [u,x,y,t]=memrecwv(a,b,alp,w,x0,y0,tmax);
else
  th=linspace(0,2*pi,81); r=linspace(0,1,20);
  [u,x,y,t]=memcirwv(r,th,r0,alp,w,tmax);
end
% Animate the solution
membanim(u,x,y,t);
function [u, x, y, t]=memrecwv (a, b, alp, w, x0, y0, tmax)
if nargin==0
  a=2; b=1; alp=1; tmax=3; w=13; x0=1.5; y0=0.5;
end
if a<b
  nx=31; ny=round(b/a*21); ny=ny+rem(ny+1,2);
else
  ny=31; nx=round(a/b*21); nx=nx+rem(nx+1,2);
end
x=linspace(0,a,nx); y=linspace(0,b,ny);
N=40; M=40; pan=pi/a*(1:N)'; pbm=pi/b*(1:M);
W=alp*sqrt(repmat(pan.^2,1,M)+repmat(pbm.^2,N,1));
wsort=sort(W(:)); wsort=reshape(wsort(1:30),5,6)';
Nt=ceil(40*tmax*alp/min(a,b));
t=tmax/(Nt-1)*(0:Nt-1);
mat=sin(x0*pan)*sin(y0*pbm)./(w^2-W.^2);
sxn=sin(x(:)*pan'); smy=sin(pbm'*y(:)');
u=zeros(ny,nx,Nt);
for j=1:Nt
  A=mat.*(cos(w*t(j))-cos(W*t(j)));
  uj=sxn*(A*smy); u(:,:,j)=uj';
end
function [u,x,y,t,r,th]=memcirwv(r,th,r0,alp,w,tmax)
if nargin==0
  r0=.4; w=15.5; th=linspace(0,2*pi,81);
  r=linspace(0,1,21); alp=1;
end
Nt=ceil(20*alp*tmax); t=tmax/(Nt-1)*(0:Nt-1);
lam=besjroot(0:20,20,1e-3);
[nj,nk]=size(lam); r=r(:)'; nr=length(r);
th=th(:); nth=length(th); nt=length(t);
N=repmat((0:nj-1)',1,nk); Nvec=N(:)';
c=besselj(N,lam*r0)./(besselj(N+1,lam).^2.*(lam.^2-w^2));
c(1,:)=c(1,:)/2; c=c(:)';
lamvec=lam(:)'; wlam=w./lamvec;
c=cos(th*Nvec).*repmat(c,nth,1);
rmat=besselj(repmat(Nvec',1,nr),lamvec'*r);
u=zeros(nth,nr,nt);
for k=1:nt
  tvec=-cos(w*t(k))+cos(lamvec*t(k));
  u(:,:,k)=c.*repmat(tvec,nth,1)*rmat;
end
u=2/pi*u; x=cos(th)*r; y=sin(th)*r;
function rts=besjroot(norder,nrts,tol) 
if nargin<3, tol=1e-5; end
jn=inline('besselj(n,x)','x','n');
N=length(norder); rts=ones(N,nrts)*nan;
opt=optimset('TolFun',tol,'TolX',tol);
for k=1:N
  n=norder(k); xmax=1.25*pi*(nrts-1/4+n/2);
  xsrch=.1:pi/4:xmax; fb=besselj(n,xsrch);
  nf=length(fb); K=find(fb(1:nf-1).*fb(2:nf)<=0);
  if length(K)<nrts
    disp('Search error in function besjroot')
    rts=nan; return
  else
    K=K(1:nrts);
    for i=1:nrts
    interval=xsrch(K(i):K(i)+1);
    rts(k,i)=fzero(jn,interval,opt,n);
    end
  end
end
function membanim(u,x,y,t)
if nargin==0;
  [u,x,y,t]=memrecwv(2,1,1,15.5,1.5,.5,5);
end
xmin=min(x(:)); xmax=max(x(:));
ymin=min(y(:)); ymax=max(y(:));
xmid=(xmin+xmax)/2; ymid=(ymin+ymax)/2;
d=max(xmax-xmin,ymax-ymin)/2; Nt=length(t);
range=[xmid-d,xmid+d,ymid-d,ymid+d, 3*min(u(:)),3*max(u(:))];
while 1 % Show the animation repeatedly
  disp(' '), disp('Press return for animation')
  dumy=input('or enter 0 to stop > ? ','s');
  if ~isempty(dumy)
    disp(' '), disp('All done'), break
  end
  for j=1:Nt
  surf(x,y,u(:,:,j)), axis(range)
  xlabel('x axis'), ylabel('y axis')
  zlabel('u axis'), titl=sprintf('MEMBRANE POSITION AT T=%5.2f',t(j));
  title(titl), colormap([1 1 1])
  colormap([127/255 1 212/255])
  drawnow, shg, pause(.1)
  end
end

Best Answer

The error message says it all. Bad value for axes property: 'ZLim' Values must be increasing and non-NaN. The error is unlikely happened in the code you showed. It happened in your file "untitled2.m" line 77 when you call the function membanim(). You probably didn't pass the correct parameter with proper data.
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