Mathematica中绘制隐函数的命令是ImplicitPlot
Matlab我曾经见人写过一个绘制隐函数的代码,一时找不到了,我在找找看
- function implot(fun,rangexy,ngrid)
- % Implicit plot function
- % function implot(fun,rangexy,ngrid)
- % fun is 'inline' function f(x,y)=0 (Note function written as equal to zero)
- % rangexy =[xmin,xmax,ymin,ymax] range over which x and y is ploted default(-2*pi,2*pi)
- % ngrid is the number of grid points used to calculate the plot,
- % Start with course grid (ngrid =20) and then use finer grid if necessary
- % default ngrid=50
- %
- % Example
- % Plot y^3+exp(y)-tanh(x)=0
- %
- % write function f as an 'inline' function of x and y-- right hand side
- % equal to zero
- %
- % f=inline('y^3+exp(y)-tanh(x)','x','y')
- % implot(f,[-3 3 -2 1])
- % A.Jutan UWO 2-2-98 <a href="mailto:ajutan@julian.uwo.ca" target="_blank">ajutan@julian.uwo.ca</a>
- if nargin == 1 ;% grid value and ranges not specified calculate default
- rangexy=[-2*pi,2*pi,-2*pi,2*pi];
- ngrid=50;
- end
- if nargin == 2; % grid value not specified
- ngrid=50;
- end
- % get 2-D grid for x and y
- xm=linspace(rangexy(1),rangexy(2),ngrid);
- ym=linspace(rangexy(3),rangexy(4),ngrid);
- [x,y]=meshgrid(xm,ym);
- fvector=vectorize(fun);% vectorize the inline function to handle vectors of x y
- fvalues=feval(fvector,x,y); %calculate with feval-this works if fvector is an m file too
- %fvalues=fvector(x,y); % can also calculate directly from the vectorized inline function
- contour(x,y,fvalues,[0,0],'b-');% plot single contour at f(x,y)=0, blue lines
- xlabel('x');ylabel('y'); grid
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[ 本帖最后由 ChaChing 于 2010-7-2 14:53 编辑 ] |