for i=1:length(y)
    if isreal(y(i)) && y(i)>400 %ÅжÏy(i)ÊÇ·ñÊÇʵÊý£¬²¢ÇÒÊÇ·ñ´óÓÚ400
        fprintf(1, '%.9f\n', y(i));
    end
end

syms x y; %×¢ÒâÓõ½µÄ·ûºÅ¶¼ÒªÉùÃ÷Ò»ÏÂ
a=y+1;
b=y-1;

f=a*b+a+b*x+y+6*x+2;

%½â·½³Ìf=0
equation = [char(f) ' = 0'];
A=solve(equation, 'y');

%ÉÏÃæ½âµÃµÄ½á¹ûÊÇ
%A =
%  - x/2 - (x^2 - 16*x - 4)^(1/2)/2 - 1
%   (x^2 - 16*x - 4)^(1/2)/2 - x/2 - 1

%¶ÔÓÚ·ûºÅʽ×Ó£¬Ê¹ÓÃsubsº¯Êý´úÈëÊýÖµ

%×¢ÒâÉÏÃæµÄ·½³ÌÒòΪÓпª·½£¬ËùÒÔ²»Ò»¶¨Äܽâ³öʵÊý½â£¬ÕâÀïÖ±½ÓÈ¡Ò»¶ÎÓÐʵÊý½âµÄ
x = 20:80;
y1 = zeros(1, length(x)); %Ï°¹ßÉÏÑ­»·Ç°Ïȸø¶¨´æ´¢¿Õ¼ä
y2 = zeros(1, length(x));
for i=1:length(x)
    y1(i) = subs(A(1), x(i));
    y2(i) = subs(A(2), x(i));
end

plot(x, y1, 'b', x, y2, 'r');

x = 20:80;
Y= subs(A, x);
plot(x, Y(1, :), 'b', x, Y(2, :), 'r');

2Â¥: Originally posted by sudo at 2011-10-12 10:12:19:
Äã²»ÓÃÿ´Î¶¼·ÅÄÇô¶à·ÖÉÏÀ´µÄ...

(1)ʹÓÃisrealº¯ÊýºÍÑ­»·
[code]
for i=1:length(y)
    if isreal(y(i)) && y(i)>400 %ÅжÏy(i)ÊÇ·ñÊÇʵÊý£¬²¢ÇÒÊÇ·ñ´óÓÚ400
        fprintf(1, '%.9f ...

5Â¥: Originally posted by sudo at 2011-10-13 20:28:33:
»¹ÊÇÌù³öÄãµÄÈ«²¿³ÌÐò°É

5Â¥: Originally posted by sudo at 2011-10-13 20:28:33:
»¹ÊÇÌù³öÄãµÄÈ«²¿³ÌÐò°É

solve('x^4+x+c=0','x')

clear
clc

%ÊäÈëƽ̨ϵͳ²ÎÊý
display('ÊäÈëƽ̨ϵͳ²ÎÊý');
% d=input('Ì«Ñô¹âÎüÊÕÍ¿²ã¿í¶Èd(m):');
% D=input('²£Á§¹ÜµÄÖ±¾¶D(m):');
% D_tro=input('·´Éä¾µ¿í¶È(m):');
% L=input('ƽ̨ϵͳ³¤¶È(m):');
% E_p=input('Ì«Ñô¹âÑ¡ÔñÎüÊÕÍ¿²ãµÄ·øÉäÂÊ:');
% E_g=input('²£Á§µÄ·øÉäÂÊ:');
% E_tro=input('·´Éä¾µµÄ·øÉäÂÊ:');
% E_rear=input('ÀäÈ´¹Ü±³²¿µÄ·øÉäÂÊ:');
% a_rear=input('ÀäÈ´¹Ü±³²¿µÄÎüÊÕÂÊ:');
d=0.06;
D=0.12;
D_tro=3;
L=6;
E_p=0.05;
E_g=0.2;
E_tro=0.2;
E_rear=0.2;
a_rear=0.8;

%ÊäÈëÖÜΧ»·¾³²ÎÊý
display('ÊäÈëÖÜΧ»·¾³²ÎÊý')
% v=input('ÖÜΧ»·¾³·çËÙ(m/s):');
% Ta=input('»·¾³¿ÕÆøζÈTa(K)£º');
% Tc=input('ÀäÈ´¹ÜζÈTc(K):');
v=1.5;
Ta=300;
Tc=323;

%³£Êý
%˹µÙ·Ò£­²¨¶û×ÈÂü³£Êý
sigma=5.667e-8;  % W/(m2.K4)



%¶¨Òå²£Á§¹ÜζÈTgΪ±äÁ¿
syms Tg Tp


%%%Ì«ÑôÄÜÈȵçϵͳÈÈËðºÄϵÊýÈçÏÂ%%%
%£¨1£©Ì«Ñô¹âÑ¡ÔñÎüÊÕÍ¿²ãÓë²£Á§¹Üϲ¿Ö®¼ä·øÉ䣺
hr_sg=sigma*(Tp^2+Tg^2)*(Tp+Tg)/(1/E_p+1/E_g-1);
Ap=d*L;
R1=1/(hr_sg*Ap);
%£¨2£©²£Á§¹ÜÉϲ¿ÓëÀäÈ´¹ÜÖ®¼äµÄ·øÉ䣺
hr_rg=sigma*(Tc^2+Tg^2)*(Tc+Tg)/(E_rear+E_g-1);
R2=1/(hr_rg*Ap);
%£¨3£©²£Á§¹Üϲ¿Óë·´Éä¾µÖ®¼ä·øÉ䣺
hr_gtro=sigma*(Tg^2+Ta^2)*(Tg+Ta)/(E_g+E_tro-1);
Ag=pi*D*L;
R3=1/(hr_gtro*0.5*Ag);
%£¨4£©²£Á§¹Üϲ¿Óë·´Éä¾µÖ®¼ä¿ÕÆø¶ÔÁ÷£º
hw=5.7+3.8*v;  % W/(m2.K)
R4=1/(hw*0.5*Ag);
%(5)·´Éä¾µÓëÖÜΧ»·¾³¿ÕÆø¶ÔÁ÷£º
%ÂÔ
%£¨6£©²£Á§¹ÜÉϲ¿¶ÔÌì¿ÕµÄ·øÉ䣺
hr_gsky=sigma*(Tg^2+Ta^2)*(Tg+Ta)*E_g;
R6=1/(hr_gsky*0.5*Ag);
%£¨7£©·´Éä¾µ¶ÔÌì¿ÕµÄ·øÉ䣺
%ÂÔ
%£¨8£©²£Á§¹ÜÉϲ¿ÓëÖÜΧ»·¾³¿ÕÆø¶ÔÁ÷£º
R8=1/(hw*0.5*Ag);

%Çó½âTg
f=(Tp-Tg)/R1+(Tc-Tg)/R2-(Tg-Ta)*(1/R3+1/R4+1/R6+1/R8);

%ÇóÊýÖµ½â
tp = 450:650; %ÒòΪÉÏÃæfÀïÃæµÄTp»¹ÓÐÓã¬ËùÒÔÕâÀï²»ÄÜͬÃû
tg = zeros(1, length(tp));

for i = 1:length(tp)
    tf = subs(f, Tp, tp(i)); %¸øTp´úÈëÖµ
    fHandle = inline(char(tf), 'Tg'); %½«tfÊÓΪº¯Êý¾ä±ú£¬'Tg'Ϊ×Ô±äÁ¿
   
    %ÔÚTg=400¸½½üµÄʵÊýÓòÕҽ⣬Èç¹ûÕÒ²»µ½»á·µ»ØNaN
    tg(i) = fzero(fHandle, 400);
   
    if tg(i)<=400
        tg(i) = 0; %Èç¹ûûÕÒµ½´óÓÚ400µÄ½â£¬ÄÇô¾ÍÖÃΪ0±íʾûÕÒµ½
    end
end

plot(tp, tg);