Matlab的等效枫树densityplot

Question

我想创建此函数的密度曲线图：

在枫木，人们可以使用所述densityplot函数来实现这一点（在末尾代码），这给：

但是，我不知道用什么密谋在MATLAB相似的身影。

这里是我当前的MATLAB代码：

x = [0:10:100]; 
y = [-50:10:50]; 
s = [10, 0]; 
i = [50,25]; 
for ii = 1 : length(x) 
    sir(ii) = -10 * 9.8 * log10((power((x(ii) - s(1)),2) + power((y(ii) - s(2)),2))/(power((x(ii) - i(1)),2) + power((y(ii) - i(2)),2))); 
end 

可能有人建议在MATLAB等效？

---

对于华普密度图，我用

densityplot(sir(x,y), x=0..100, y=-50..50, axes=boxed, style=patchnogrid, scaletorange=-5..50, colorscheme = [black, "green", "white"]) 

Answer 1

可以使用surf（三维曲面图）来实现这一点，但你需要一个更精细的网格比它的10个步骤为了看上去好点！

您还需要meshgrid才能获得所有组合的x和y坐标。

请参阅有关进一步的细节的意见。

% Set up grid points 
x = 0:0.1:100; 
y = -50:0.1:50; 
[x,y] = meshgrid(x,y); 
% Set up parameters i, s and g 
i = [50 25]; s = [10 0]; g = 9.8; 
% Work out density 
% - no need for loop if we use element-wise operations ./ and .^ 
% - power(z,2) replaced by z.^2 (same function, more concise) 
% - You forgot the sqare roots in your question's code, included using .^(1/2) 
% - line continuation with "...", could remove and have on one line 
sir = -10*g*log10(((x-s(1)).^2 + (y-s(2)).^2).^(1/2) ./ ... 
        ((x-i(1)).^2 + (y-i(2)).^2).^(1/2)  ); 
% Plot, and set to a view from above 
surf(x,y,sir,'edgecolor','none','facecolor','interp'); 
view(2); 
% Change the colour scheme 
colormap('bone') 

结果：

匹配您的例子

您使用的枫叶命令scaletorange=-5..50。这限制-5和50（docs）之间的规模，这样以来sir是我们的规模可变的，我们应该限制它一样。在MATLAB：

% Restrict sir to the range [-5,50] 
sir = min(max(sir,-5),50); 
% Of course we now have to replot 
surf(x,y,sir,'edgecolor','none','facecolor','interp'); 
view(2); 

现在，如果你想黑/绿颜色，你可以使用自定义colormap，这也将理顺造成'bone'colormap唯一有64种颜色的条纹。

% Define the three colours to interpolate between, and n interpolation points 
black = [0 0 0]; green = [0 1 0]; white = [1 1 1]; 
n = 1000; 
% Do colour interpolation, equivalent to Maple's 'colorscheme = [black, "green", "white"]' 
% We need an nx3 matrix of colours (columns R,G,B), which we get using interp1 
colormap(interp1(1:3, [black; green; white], linspace(1,3,n))); 

随着g=3.5（不知道你用什么），我们得到几乎相同的情节