Problem plotting a 3-D function

Question

Ben 2013-5-16

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/76002-problem-plotting-a-3-d-function

Hi there

I need to plot 2 3-D functions an see how they intersect. However I am experiencing problems with one of the functions (z1). Apparently i am calculating it wrong, therefor my input for z1 is wrong. Can somebody help me? This should be rather easy for someone with experience ;)

This is the code:

% Define the input grid
clc, clear, close all
[x, y] = meshgrid(linspace(0,400,40),linspace(0,30000,40));
grid on
xlabel('Stress [MPa]')
ylabel('Time [h]')
zlabel('Creep Strain [-]')
% Calculate the two surfaces
A1 = -8.269000000000000;
m1 = 2.071000000000000;
m2 = 0.239700000000000;
B1 = -13.100000000000000;
n1 = 2.813000000000000;
B2 = -49.960000000000001;
n2 = 18.170000000000002;
z1 = 10^A1*x.^m1*y.^m2+y.*(10^B1*x.^n1+10^B2*x.^n2);
z2 = 0*x+0*y+0.01;
% Visualize the two surfaces
surface(x, y, z1, 'FaceColor', [0.5 1.0 0.5], 'EdgeColor', 'none');
surface(x, y, z2, 'FaceColor', [1.0 0.5 0.0], 'EdgeColor', 'none');
view(3); camlight; axis vis3d

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Answer 1

David Sanchez 2013-5-16

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/76002-problem-plotting-a-3-d-function#answer_85667

在 MATLAB Online 中打开

try to hold on the current figure and change your point of view:

% Define the input grid clc, clear, close all 
[x, y] = meshgrid(linspace(0,400,40),linspace(0,30000,40)); 
grid on 
xlabel('Stress [MPa]') 
ylabel('Time [h]') 
zlabel('Creep Strain [-]')
% Calculate the two surfaces 
A1 = -8.269000000000000; 
m1 = 2.071000000000000; 
m2 = 0.239700000000000; 
B1 = -13.100000000000000; 
n1 = 2.813000000000000; 
B2 = -49.960000000000001; 
n2 = 18.170000000000002; 
z1 = 10^A1*x.^m1*y.^m2+y.*(10^B1*x.^n1+10^B2*x.^n2);
z2 = 0*x+0*y+0.01;
% Visualize the two surfaces 
surface(x, y, z1, 'FaceColor', [0.5 1.0 0.5], 'EdgeColor', 'none'); hold on
surface(x, y, z2, 'FaceColor', [1.0 0.5 0.0], 'EdgeColor', 'none'); hold off
view([30,30]); 
camlight; 
axis vis3d

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David Sanchez 2013-5-16

在 MATLAB Online 中打开

Is your z1 function this one?

z1 = (10^A1).*(x.^m1).*(y.^m2) + y.*( (10^B1).*(x.^n1) + (10^B2).*(x.^n2) );

Since we don't know your function, there is no way to help you further. Could you be more specific?

Ben 2013-5-16

yes that is the function z1! if you for example enter x = 1 and y = 1 you will get other results for z1(1,1) then i you use meshgrid and linspace to define x and y

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Answer 2

David Sanchez 2013-5-16

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/76002-problem-plotting-a-3-d-function#answer_85674

Well, I think you are having a scale issue. Your z1 is right, and the way to plot your data as well is right, but bear in mind the scale of your result ( z1 ). You are plotting an exponential function, and as such, there will be a big difference in the results you obtain with an insignificant change of your input values. I figure out you know that your z2 is just a plane on z=0.01. Make sure your z1 is exactly what you want.