Error in T12 (line 35) surf(X, Y, fplot) and I have no idea what I was wrong
1 Ansicht (letzte 30 Tage)
Ältere Kommentare anzeigen
clc
clear
close all
syms x y
f = @(x,y)(x.^2+y.^2+x.*y-12*log(x)-10*log(y));
fx = diff(f,x);
fy = diff(f,y);
[xc,yc] = solve(fx,fy,x,y,'real',true);
[m,n] = size([xc,yc]);
fxx = diff(fx,x);
fyy = diff(fy,y);
fxy = diff(fx,y);
D = fxx*fyy - fxy^2;
%print
for i = 1:m
if subs(D,{x,y},{xc(i),yc(i)}) > 0
if subs(fxx,{x,y},{xc(i),yc(i)}) > 0
fprintf('(%f,%f,%f) is local minimum\n',xc(i),yc(i),f(xc(i),yc(i)));
else
fprintf('(%f,%f,%f) is local maximum\n',xc(i),yc(i),f(xc(i),yc(i)));
end
elseif subs(D,{x,y},{xc(1),yc(1)}) < 0
fprintf('(%f,%f,%f) is saddle point\n',xc(i),yc(i),f(xc(i),yc(i)));
else
fprintf('(%f,%f,%f) is unknown\n',xc(i),yc(i),f(xc(i),yc(i)));
end
end
%Sketch
xx = linspace(-1.2, 1.2, 100);
yy = linspace(-1.2, 1.2, 100);
[X,Y] = meshgrid(xx, yy);
fplot = X^2+Y^2-12*log(X)-10*log(Y)+X*Y;
figure
surf(X, Y, fplot)
hold on
for i = 1:m
plot3(xc(i),yc(i),f(xc(i),yc(i)),'r*')
end
0 Kommentare
Akzeptierte Antwort
KSSV
am 17 Mai 2022
clc
clear
close all
syms x y
f = @(x,y)(x.^2+y.^2+x.*y-12*log(x)-10*log(y));
fx = diff(f,x);
fy = diff(f,y);
[xc,yc] = solve(fx,fy,x,y,'real',true);
[m,n] = size([xc,yc]);
fxx = diff(fx,x);
fyy = diff(fy,y);
fxy = diff(fx,y);
D = fxx*fyy - fxy^2;
%print
for i = 1:m
if subs(D,{x,y},{xc(i),yc(i)}) > 0
if subs(fxx,{x,y},{xc(i),yc(i)}) > 0
fprintf('(%f,%f,%f) is local minimum\n',xc(i),yc(i),f(xc(i),yc(i)));
else
fprintf('(%f,%f,%f) is local maximum\n',xc(i),yc(i),f(xc(i),yc(i)));
end
elseif subs(D,{x,y},{xc(1),yc(1)}) < 0
fprintf('(%f,%f,%f) is saddle point\n',xc(i),yc(i),f(xc(i),yc(i)));
else
fprintf('(%f,%f,%f) is unknown\n',xc(i),yc(i),f(xc(i),yc(i)));
end
end
%Sketch
xx = linspace(-1.2, 1.2, 100);
yy = linspace(-1.2, 1.2, 100);
[X,Y] = meshgrid(xx, yy);
Z = X.^2+Y.^2-12*log(X)-10*log(Y)+X.*Y; %<---- element by element operations
figure
surf(X, Y, abs(Z))
hold on
for i = 1:m
plot3(xc(i),yc(i),f(xc(i),yc(i)),'r*')
end
0 Kommentare
Weitere Antworten (0)
Siehe auch
Kategorien
Mehr zu Number Theory finden Sie in Help Center und File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!