Error function definition not supported in this context create functions in code file - Исправление ошибок и поиск оптимальных решений проблем

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Trying to do : function nrm = fournorm(x) for a question

But it comes up with Error: Function definition not supported in this context. Create functions in code file.

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Where are you trying to do it?

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«Matlab on command window»

Not possible.

Functions may be either:

defined in a file with the function declaration, or
defined as an anonymous function.

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Im trying to solve a maths question and this is what it tells me to do as the first step:

function nrm = fournorm(x) % find the four-norm of the vector x

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«…this is what it tells me to do as the first step:»

You need to write that code in a file and save the file using the same name as the function, i.e. fournorm.m.

In MATLAB it is not possible to define functions like that in the command window.

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If you have simpler functions like

function y = cubicPoly(x)

y = x.^3 + x.^2 + x + 1;

end

then you can make use of function_handle and define such functions in command window itself or in a script as follows:

f = @(x) x.^3 + x.^2 + x + 1;

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To be clearer, you cannot define a function simply by copying and pasting the code starting with the function keyword at the prompt in the MATLAB Command Window. The function keyword is only allowed inside a script, function, or class file.

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编辑：Rik

2021-10-7

function move=tictac(n). %first computer move in tic-tac-toe. %go for the centre if empty. %otherwise choose the upper left corner. if n=5 move=5; else move=1 end

(Can anyone help me with this.can u tell me why matlab software shows Error: Function definition are not

supported in this context. Functions

can only be created as local or nested

functions in code files.

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Did you figure it out? I’m having a similar issue.

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Yeah i made a little change in the function

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what is the change , i got same issue

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Yeah i write function in file «tictac.mm» like this. This is code file

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After this , where we apply function write any value of functions u will get value

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Below is my code to solve the parallel plate capacitor problem.

clear all
x=linspace(1,20,10);
y=linspace(1,20,10);
[X,Y]=meshgrid(x,y);
C=delaunay(X(:),Y(:));
xy=[X(:) Y(:)];



  


                       
  



Np=length(xy);
S=MatGlob(xy,C);
F=sparse(Np,1);
V0=1;
G=1e12;
for k=1:Np;
if x(k)==1
S(k,k)=S(k,k)+G;
F(k)=G*(-V0);
if x(k)==20



  


                       
  



S(k,k)=S(k,k)+G;
F(k)=G*(+V0);
end
V=SF;
figure
plot(xy,V,'*-')
title('potential(V)')
xlabel('postition(m)')
ylabel('postition(m)')
hold on



  


                       
  



function S=MatGlob(xy,C)
Np=length(xy);
S=sparse(Np,Np);
Epsr=3.5;
Ne=size(C,1);
for k=1:Ne
    N=C(k,:);
    x1=xy(N(1),1);
    x2=xy(N(2),1);
    x3=xy(N(3),1);



  


                       
  



    y1=xy(N(1),2);
    y2=xy(N(2),2);
    y3=xy(N(3),2);
    abc1=[1 x1 y1;1 x2 y2;1 x3 y3][1;0;0];



  


                       
  



    abc2=[1 x1 y1;1 x2 y2;1 x3 y3][0;1;0];
    abc3=[1 x1 y1;1 x2 y2;1 x3 y3][0;0;1];
    Grad=[abc1(2) abc2(2) abc3(2); abc1(3) abc2(3) abc3(3)];
    Se=Epsr*(Grad'*Grad)*abs((x2-x1)*(y3-y1)-(x3-x1)*(y2-y1))/2;
    S(N,N)=S(N,N)+Se;
end



  


                       
  



end

Yet, Matlab annouce the error as follows: «Function definition not supported in this context. Create functions in code file» Would you please help me to fix this error? Thank you in advance.

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 clc; clear; close all;% Очистка памяти и экрана, закрытие окон 
 
 global rSphere mSphere g cxSphere cxWing k; 
 global sWing vSphere sSphere mu0; 
 
 %независимые от слоя параметры 
 rSphere = 0.45; %радиус сферы, м 
 mSphere = 230; %масса сферы, кг 
 g = 9.8066; %ускорение свободного падения, м/с^2 
 cxSphere = 0.47; %коэффициент сопротивления сферы (от числа Рей-нольдса), безразмерный 
 cxWing = 0.045; %коэффициент сопротивления крыла (от числа Рей-нольдса), безразмерный 
 lWing = 0.5; %размах крыла, м 
 lambda = 5; %удлинение крыла 
 k = 0.9*pi; %уточняющий коэффициент 
 c0 = lWing/lambda; %средняя хорда = центральная хорда, м 
 thickOfWing = 16; %относительная максимальная толщина, % 
 sWing = lWing*((c0*thickOfWing)/100); %площадь характерного сече-ния крыла, м^2 
 vSphere = (4/3)*pi*(rSphere.^3); %объем сферы, м^3 
 sSphere = pi*(rSphere.^2); %плошадь сферы, м^2 
 mu0 = (k*c0)/(2*lWing); 
 
 %[H rhoWater W alpha] изменение параметров в слоях% 
 waterLayers = [70 1025 -0.1 -0.2 
 130 1050 0.15 0.2]; 
 %где H - толщина слоя, м; 
 %rhoWater - плотность воды в слое, кг/м^3; 
 %W - скорость сдивого течения, м/с; 
 %alpha0 - %угол между хордой крыла и осью y 
 %первая строка в матрице - первый слой от поверхности, 
 %вторая строка в матрице - второй слой от поверхности и тд.
 
 dt = 1; %шаг изменения времени, c 
 
 figure(1); hold on 
 grid on 
 xlabel('x') 
 ylabel('y') 
 
 %рисуем траектории, не предполагая малость угла delta 
 %рисуем траектории, предполагая малость угла delta 
 waterLayers(:,4) = [0; 0]; 
 DrawTrajectoryAF(@RungeKuzn, waterLayers, dt, 'b'); 
 DrawTrajectoryAF(@Runge, waterLayers, dt, 'g'); 
 
 waterLayers(:,4) = [0.2; 0.2]; 
 DrawTrajectoryAF(@Runge, waterLayers, dt, 'r'); 
 DrawTrajectoryAF(@RungeKuzn, waterLayers, dt, 'y'); 
 hold off 
  
 figure(2); hold on 
 grid on 
 xlabel('x') 
 ylabel('y') 
 
 dt = 1; 
 waterLayers = [70 1025 0 -0.2 
 130 1050 0 0.2]; 
 
 DrawTrajectoryAF(@Runge, waterLayers, dt, 'b'); 
 DrawTrajectoryAF(@Runge, waterLayers, dt, 'r', @AlphaFuncTcos); 
 DrawTrajectoryAF(@Runge, waterLayers, dt, 'g', @AlphaFuncTline); 
 hold off 
  
 figure(3); hold on 
 grid on 
 xlabel('x') 
 ylabel('y') 
 
 dt = 1; 
 waterLayers = [70 1025 0 -0.2 
 130 1050 0 0.2]; 
 
 DrawTrajectoryAF(@Runge, waterLayers, dt, 'r', @AlphaFuncYline); 
 DrawTrajectoryAF(@Runge, waterLayers, dt, 'b', @AlphaFuncXline); 
 hold off 
 
figure(4); hold on 
 grid on 
 xlabel('x') 
 ylabel('y') 
 
 dt = 1; 
 
 DrawTrajectoryAT(@Runge, waterLayers, dt, 'b', @AlphaFuncTable); 
 hold off 
 
 function [alpha0] = AlphaFuncTcos(t,x,y) 
 alpha0 = -0.2*cos(t/12); 
 end 
 
 function [alpha0] = AlphaFuncTline(t,x,y) 
 alpha0 = -0.01*t + 0.2; 
 end 
 
 function [alpha0] = AlphaFuncYline(t,x,y) 
 alpha0 = 0.001*y - 0.2; 
 end 
 
 function [alpha0] = AlphaFuncXline(t,x,y) 
 alpha0 = -0.1*x + 0.2; 
 end 
 
 function [alpha0] = AlphaFuncTable(t,x,y, nOfLayer, alpha0) 
 
 global tIndex xPosIndex xNegIndex yIndex 
 
 %[t alpha0] 
 timeCond = [0 0.2; 10 -0.2; 25 0]; 
 %[nOfLayer x alpha0] 
 xPositiveCond = [1 1 0.1; 1 3 0.05; 1 6 -0.2]; 
 %[nOfLayer x alpha0] 
 xNegativeCond = [2 -0.5 0.1; 2 -2 0.05; 2 4 -0.2]; 
 %[y alpha0] 
 yCond = [5 0.2; 100 0.1; 140 -0.2]; 
 
 if tIndex <= size(timeCond,1) && t >= timeCond (tIndex, 1) 
 alpha0 = timeCond(tIndex , 2); 
 tIndex = tIndex + 1; 
 end 
 
 if yIndex <= size(yCond,1) && y >= yCond (yIndex, 1) 
 alpha0 = yCond(yIndex , 2);
 yIndex = yIndex + 1; 
 end 
 
 if xPosIndex <= size(xPositiveCond,1)&& nOfLayer == xPositiveCond(xPosIndex, 1) && x >= xPositiveCond(xPosIndex, 2) 
 alpha0 = xPositiveCond(xPosIndex , 3); 
 xPosIndex = xPosIndex + 1; 
 end 
 
 if xNegIndex <= size(xNegativeCond,1)&& nOfLayer == xNegativeCond(xNegIndex, 1) && x <= xNegativeCond(xNegIndex, 2) 
 alpha0 = xNegativeCond(xNegIndex , 3); 
 xNegIndex = xNegIndex + 1; 
 end 
 
 end

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