How can I convert a equation into an character array?

2018 10 17
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回答已采纳
更新时间：2018 10 20
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Hi community,
I want to convert an equation like: N=1-X into an character array like: Z='N=1-X' or the other way around. The problem is functions like string2num() do not accept variables as input.

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Matt J
Matt J 2018-10-17
编辑：Matt J 2018-10-17
Convert to a character array from what? In what form does the input equation exist? As a symbolic expression?
Emre Sahin
Emre Sahin 2018-10-19
I am currently programming a GUI, where I am using in different functions different equations as the z-axis in surf plots. I also need to show the same equation as a label on the z-axis in the surf plot and on a static text field. Therefore I need to convert the function to an character array. To do that I want to use the previously defined equation without typing it all the way again.
Guillaume
Guillaume 2018-10-19
Again, as Matt asked, what form does the equation takes in your code? There are many ways to code an equation for plotting and the answer is going to depend on how you've done it.
Emre Sahin
Emre Sahin 2018-10-19
编辑：Emre Sahin 2018-10-20
I don't exactly know what you mean, I will just show an example code:
classdef Formfunctions < handle
methods(Static)
function surfplot(handles,X,Y,N)
s=surf(X,Y,N);
s.FaceColor='interp';
a=gca;
a.Box='on';
zlim([0 1]);
xlabel('x')
ylabel('y')
% I want to display the function instead of N %
zlabel('N')
% I want to show the function N on the static text field%
set(handles.text,'string', N)
end
function Node1plot(handles,X,Y)
%Nr.1%
N1=1/4*(1-X).*(1-Y);
figure('Name','Plot Formfunctions: Node1plot',...
'NumberTitle','off', 'Units', 'Normalized', ...
'OuterPosition', [0.5 0 0.5 1]);
colormap(jet)
Formfunctions.surfplot(handles,X,Y,N1)
end
function Node2plot(handles,X,Y)
%Nr.2%
N2=1/4*(1+X).*(1-Y);
figure('Name','Plot Formfunction: Node2plot',...
'NumberTitle','off', 'Units', 'Normalized', ...
'OuterPosition', [0.5 0 0.5 1]);
colormap(jet)
Formfunctions.surfplot(handles,X,Y,N2)
end
end
end
In the main function I will just have the comands:
if(blabla==bla)
Formfunctions.Node1plot(handles,X,Y);
elseif(blabla==blala)
Formfunctions.Node2plot(handles,X,Y);
end
I hope that it is know clear.

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 采纳的回答

Matt J
Matt J 2018-10-19
编辑：Matt J 2018-10-19

2 个投票

    methods(Static)  
        function surfplot(handles,X,Y,fun)  %<---change
            s=surf(X,Y,fun(X,Y));
            s.FaceColor='interp';
            a=gca;
            a.Box='on';
            zlim([0 1]);
            xlabel('x')
            ylabel('y')
            % I want to display the function instead of N %
            N=strrep( func2str(fun) ,'@(x,y)','' );  %<---change
            zlabel( N )
            % I want to show the function N on the static text field%
            set(handles.text,'string', N)
        end
        function Node1plot(handles,X,Y)  
            fun=@(x,y) 1/4*(1-x).*(1-y);  %<---change
            figure('Name','Plot Formfunctions: Node1plot',...
                   'NumberTitle','off', 'Units', 'Normalized', ...
                   'OuterPosition', [0.5 0 0.5 1]);
            colormap(jet)
            Formfunktionen.surfplot(handles,X,Y,fun)  %<---change
        end
     end

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