# Documentation of quiver3

Global Index (all files) (short | long) | Local Index (files in subdir) (short | long)

## Function Synopsis

`hh = quiver3(varargin)`

## Help text

```QUIVER3 3-D quiver plot.
QUIVER3(X,Y,Z,U,V,W) plots velocity vectors as arrows with components
(u,v,w) at the points (x,y,z).  The matrices X,Y,Z,U,V,W must all be
the same size and contain the corresponding position and velocity
components.  QUIVER3 automatically scales the arrows to fit.

QUIVER3(Z,U,V,W) plots velocity vectors at the equally spaced
surface points specified by the matrix Z.

QUIVER3(Z,U,V,W,S) or QUIVER3(X,Y,Z,U,V,W,S) automatically
scales the arrows to fit and then stretches them by S.
Use S=0 to plot the arrows without the automatic scaling.

QUIVER3(...,LINESPEC) uses the plot linestyle specified for
the velocity vectors.  Any marker in LINESPEC is drawn at the base
instead of an arrow on the tip.  Use a marker of '.' to specify
no marker at all.  See PLOT for other possibilities.

QUIVER3(...,'filled') fills any markers specified.

H = QUIVER3(...) returns a vector of line handles.

Example:
[x,y] = meshgrid(-2:.2:2,-1:.15:1);
z = x .* exp(-x.^2 - y.^2);
[u,v,w] = surfnorm(x,y,z);
quiver3(x,y,z,u,v,w); hold on, surf(x,y,z), hold off

```

## Cross-Reference Information

This function calls

## Listing of function quiver3

```function hh = quiver3(varargin)

%   Clay M. Thompson 3-3-94
%   Copyright (c) 1984-98 by The MathWorks, Inc.
%   \$Revision: 1.18 \$  \$Date: 1997/11/21 23:46:39 \$

alpha = 0.33; % Size of arrow head relative to the length of the vector
beta = 0.33;  % Width of the base of the arrow head relative to the length
autoscale = 1; % Autoscale if ~= 0 then scale by this.
plotarrows = 1;

filled = 0;
ls = '-';
ms = '';
col = '';

nin = nargin;
% Parse the string inputs
while isstr(varargin{nin}),
vv = varargin{nin};
if ~isempty(vv) & strcmp(lower(vv(1)),'f')
filled = 1;
nin = nin-1;
else
[l,c,m,msg] = colstyle(vv);
if ~isempty(msg),
error(sprintf('Unknown option "%s".',vv));
end
if ~isempty(l), ls = l; end
if ~isempty(c), col = c; end
if ~isempty(m), ms = m; plotarrows = 0; end
if isequal(m,'.'), ms = ''; end % Don't plot '.'
nin = nin-1;
end
end

error(nargchk(4,7,nin));

% Check numeric input arguments
if nin<6, % quiver3(z,u,v,w) or quiver3(z,u,v,w,s)
[msg,x,y,z] = xyzchk(varargin{1});
u = varargin{2};
v = varargin{3};
w = varargin{4};
else % quiver3(x,y,z,u,v,w) or quiver3(x,y,z,u,v,w,s)
[msg,x,y,z] = xyzchk(varargin{1:3});
u = varargin{4};
v = varargin{5};
w = varargin{6};
end
if ~isempty(msg), error(msg); end

% Scalar expand u,v,w.
if prod(size(u))==1, u = u(ones(size(x))); end
if prod(size(v))==1, v = v(ones(size(u))); end
if prod(size(w))==1, w = w(ones(size(v))); end

% Check sizes
if ~isequal(size(x),size(y),size(z),size(u),size(v),size(w))
error('The sizes of X,Y,Z,U,V, and W must all be the same.');
end

% Get autoscale value if present
if nin==5 | nin==7, % quiver3(z,u,v,w,s) or quiver3(x,y,z,u,v,w,s)
autoscale = varargin{nin};
end

if length(autoscale)>1,
error('S must be a scalar.');
end

if autoscale,
% Base autoscale value on average spacing in the x and y
% directions.  Estimate number of points in each direction as
% either the size of the input arrays or the effective square
% spacing if x and y are vectors.
if min(size(x))==1, n=sqrt(prod(size(x))); m=n; else [m,n]=size(x); end
delx = diff([min(x(:)) max(x(:))])/n;
dely = diff([min(y(:)) max(y(:))])/m;
delz = diff([min(z(:)) max(y(:))])/max(m,n);
del = sqrt(delx.^2 + dely.^2 + delz.^2);
len = sqrt((u/del).^2 + (v/del).^2 + (w/del).^2);
autoscale = autoscale*0.9 / max(len(:));
u = u*autoscale; v = v*autoscale; w = w*autoscale;
end

ax = newplot;
next = lower(get(ax,'NextPlot'));
hold_state = ishold;

% Make velocity vectors
x = x(:).'; y = y(:).'; z = z(:).';
u = u(:).'; v = v(:).'; w = w(:).';
uu = [x;x+u;repmat(NaN,size(u))];
vv = [y;y+v;repmat(NaN,size(u))];
ww = [z;z+w;repmat(NaN,size(u))];

h1 = plot3(uu(:),vv(:),ww(:),[col ls]);

if plotarrows,
beta = beta * sqrt(u.*u + v.*v + w.*w) ./ (sqrt(u.*u + v.*v) + eps);

% Make arrow heads and plot them
hu = [x+u-alpha*(u+beta.*(v+eps));x+u; ...
x+u-alpha*(u-beta.*(v+eps));repmat(NaN,size(u))];
hv = [y+v-alpha*(v-beta.*(u+eps));y+v; ...
y+v-alpha*(v+beta.*(u+eps));repmat(NaN,size(v))];
hw = [z+w-alpha*w;z+w;z+w-alpha*w;repmat(NaN,size(w))];

hold on
h2 = plot3(hu(:),hv(:),hw(:),[col ls]);
else
h2 = [];
end

if ~isempty(ms), % Plot marker on base
hu = x; hv = y; hw = z;
hold on
h3 = plot3(hu(:),hv(:),hw(:),[col ms]);
if filled, set(h3,'markerfacecolor',get(h1,'color')); end
else
h3 = [];
end

if ~hold_state, hold off, view(3); grid on, set(ax,'NextPlot',next); end

if nargout>0, hh = [h1;h2;h3]; end
```