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<P>% 画三维隐式曲面f(x,y,z)=0,fun为函数表达式,s为变量名称列表(默认为x,y,z),range_xyz为x,y,z范围,ngrid为网格剖分数<BR>function test=implot3(fun,range_xyz,ngrid,s)<BR>if nargin==0 %无参数时,默认在区域[-1,1, -1,1,-1,1]画单位园,网格剖分为20<BR> fun=inline('x^2+y^2+z^2-1','x','y','z');<BR> s=[sym('x'),sym('y'),sym('z')];<BR> range_xyz=[-1,1,-1,1,-1,1];<BR> ngrid=20;<BR>end<BR>if nargin==1 <BR> s=[sym('x'),sym('y'),sym('z')];<BR> range_xyz=[-1,1,-1,1,-1,1];<BR> ngrid=20;<BR>end<BR>if nargin==2<BR> s=[sym('x'),sym('y'),sym('z')];<BR> ngrid=20;<BR>end<BR>if nargin==3<BR> s=[sym('x'),sym('y'),sym('z')];<BR>end<BR>xm=linspace(range_xyz(1),range_xyz(2),ngrid);<BR>ym=linspace(range_xyz(3),range_xyz(4),ngrid);<BR>zm=linspace(range_xyz(5),range_xyz(6),ngrid);<BR>[xx,yy,zz]=meshgrid(xm,ym,zm);<BR>%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<BR>%%%%%%%%%%%%%%%% inline形式的可通过sym(char(fun))化为sym形式的,实际上以下这段代<BR>%%%%%%%%%%%%%%%% 码可以省去,<BR>%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<BR>if isa(fun,'inline')%%%判断fun是否inline型,是的话返回1,否则返回0<BR> c=findsym(sym(char(fun)));<BR> for k=1:3:length(c);<BR> w1(1+(k-1)/3)=sym(c(k));<BR> end<BR> f=vectorize(fun);%vectorize函数举例:fun=inline('x^2+y^2+z^2-1','x','y','z'),则f=x.^2+y.^2+z.^2-1,即在^前加了个“.”号<BR> if length(w1)==3 %%如果变量个数为3时执行的命令<BR> fvalues=feval(f,xx,yy,zz);<BR> elseif length(w1)==2 %%如果变量个数为2时执行的命令<BR> if char(w1(1))==char(s(1))&char(w1(2))==char(s(2))<BR> fvalues=feval(f,xx,yy);<BR> end<BR> if char(w1(1))==char(s(1))&char(w1(2))==char(s(3))<BR> fvalues=feval(f,xx,zz);<BR> end <BR> if char(w1(1))==char(s(2))&char(w1(2))==char(s(3))<BR> fvalues=feval(f,yy,zz);<BR> end <BR> elseif length(w)==1 %%如果变量个数为1时执行的命令<BR> if char(w1(1))==char(s(1))<BR> fvalues=feval(f,xx);<BR> end<BR> if char(w1(1))==char(s(2))<BR> fvalues=feval(f,yy);<BR> end<BR> if char(w1(1))==char(s(3))<BR> fvalues=feval(f,zz);<BR> end<BR> else<BR> test=length(w);<BR> return;%error('error');<BR> end<BR>end<BR>%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%<BR>if isa(fun,'sym')%%%判断fun是否sym型,是的话返回1,否则返回0<BR> r=findsym(fun); %%%%找到sym型的fun中变量的个数,返回的r为char类型,所以之后的一个for循环将char转化为sym<BR> for k=1:3:length(r)<BR> w(1+(k-1)/3)=sym(r(k));%因为如果有三个变量,则r=[x, y, z],即有7个元素:r(1)=x,r(2)=逗号,r(3)=空格,........<BR> end<BR> if length(w)==3 %%如果变量个数为3时执行的命令<BR> fvalues=subs(fun,w,{xx,yy,zz});<BR> elseif length(w)==2 %%如果变量个数为2时执行的命令<BR> if char(w(1))==char(s(1))&char(w(2))==char(s(2))<BR> fvalues=subs(fun,w,{xx,yy});<BR> end<BR> if char(w(1))==char(s(1))&char(w(2))==char(s(3))<BR> fvalues=subs(fun,w,{xx,zz});<BR> end <BR> if char(w(1))==char(s(2))&char(w(2))==char(s(3))<BR> fvalues=subs(fun,w,{yy,zz});<BR> end <BR> elseif length(w)==1 %%如果变量个数为1时执行的命令<BR> if char(w(1))==char(s(1))<BR> fvalues=subs(fun,w,{xx});<BR> end<BR> if char(w(1))==char(s(2))<BR> fvalues=subs(fun,w,{yy});<BR> end<BR> if char(w(1))==char(s(3))<BR> fvalues=subs(fun,w,{zz});<BR> end<BR> else<BR> test=length(w);<BR> return;%error('error');<BR> end<BR>end<BR>isosurface(xx,yy,zz,fvalues,0); %p=isosurface(x,y,z,fvalues,0); %set(p, 'FaceColor', 'interp', 'EdgeColor', 'red');<BR>xlabel('x');<BR>ylabel('y');<BR>zlabel('z');<BR>grid;<BR><BR>写的有点罗唆了,不过可以用<BR>>>fun=inline('-z^2+3*x^2+y^2-8*x*y-6')<BR><BR>fun =</P>
<P> Inline function:<BR> fun(x,y,z) = -z^2+3*x^2+y^2-8*x*y-6<BR>>>implot3(fun,[-2*pi,2*pi,-2*pi,2*pi,-2*pi,2*pi])<BR></P> |
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