How can I vectorize a function?

144 次查看（过去 30 天）

显示更早的评论

David Franco 2018-3-1

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/385717-how-can-i-vectorize-a-function

评论： Star Strider 2018-3-24

采纳的回答： Star Strider

The function I want to vectorize is Cross-in-Tray Function (2-D):

f(X,Y) = -0.0001*(abs(sin(X)*sin(Y)*exp(abs(100-sqrt(X^2+Y^2)/pi)))+1)^0.1;

I want to use the command (to plot the function):

fsurf(@(x,y) crossintrayfcn([x,y]))

I have this two function codes:

function z = crossintrayfcn(xx)
x = xx(:,1);
y = xx(:,2);
expcomponent = abs(100-(sqrt(x.^2 + y.^2)/pi));
z = -0.0001*((abs(sin(x).*sin(y).*exp(expcomponent))+1).^0.1);
end

And:

function [y] = crossintrayfcn(xx)
x1 = xx(1);
x2 = xx(2);
fact1 = sin(x1)*sin(x2);
fact2 = exp(abs(100 - sqrt(x1^2 + x2^2)/pi));
y = -0.0001 * (abs(fact1*fact2) + 1)^0.1;
end

But they plot nothing!

Thanks!

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

采纳的回答

Star Strider 2018-3-1

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/385717-how-can-i-vectorize-a-function#answer_307862

Vectorising it simply requires using element-wise operations:

f = @(X,Y) -0.0001*(abs(sin(X).*sin(Y).*exp(abs(100-sqrt(X.^2+Y.^2)/pi)))+1).^0.1;
[x,y] = meshgrid(linspace(-10, 10, 49));
figure
surfc(x, y, f(x,y))
grid on

See the documentation on Array vs. Matrix Operations (link) and Vectorization (link) for details.

9 个评论
显示 7更早的评论隐藏 7更早的评论

Yair Altman 2018-3-24

@StarStrider - thanks, duly noted

Star Strider 2018-3-24

@Yair — My pleasure.

请先登录，再进行评论。

更多回答（1 个）

David Franco 2018-3-5

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/385717-how-can-i-vectorize-a-function#answer_308500

Because of the above problems I'm using my own function with surfc to replace fsurf:

function z = plotfcn(fcn,range,grid,shad)
% PLOTFCN evaluate and plot a 3D function
% INPUT:
%    FCN   - @myFunction (function handle)
%    RANGE - [x1min x1 max x2min x2max] (default = [-10 10 -10 10])
%    GRID  - grid size for the function evaluation (default = 101)
%    SHAD  - set color shading properties (default = 0)
%            0 = faceted (continued colormap with black mesh lines)
%            1 = interp (interpolated colormap)
%            2 = flat (continued colormap)
% OUTPUT:
%    Z     - function eval (GRID x GRID)
% EXAMPLE:
% z = plotfcn2(@ackleyfcn, [-32 32; -32 32], 200, 1);
switch nargin
    case 4
    case 3
        shad = 0;
    case 2
        shad = 0;
        grid = 101;
    case 1
        shad = 0;
        grid = 101;
        range = [-10 10 -10 10];
    otherwise
        disp('Not enough input arguments. Function required.')
        return
end
x1 = meshgrid(linspace(range(1,1), range(1,2), grid));
x2 = meshgrid(linspace(range(1,3), range(1,4), grid))';
xx = [x1(:),x2(:)];
f = fcn(xx);
f = reshape(f,size(x1));
if nargout == 1
    z = f;
end
figure
surfc(x1,x2,f)
title([func2str(fcn), ' [x,y]'])
colormap jet
if shad == 1
    shading interp
elseif shad == 2
    shading flat
end
end