"Unable to perform assignment because the left and right sides have a different number of elements"

Hi, my code has the following error:

"Unable to perform assignment because the left and right sides have a different number of elements.

Error in sym/privsubsasgn (line 1126)

L_tilde2 = builtin('subsasgn',L_tilde,struct('type','()','subs',{varargin}),R_tilde);

Error in sym/subsasgn (line 963)

C = privsubsasgn(L,R,inds{:});

Error in main (line 49)

S(j) = solve(eqn, DegU, 'Real', true);"

My code is as follows:

 x = ones(1,26);
 alpha = (4*10^-3)/(4.8*10^-2);
 [phos_rate] = (0.01:0.001:0.035);

 for i = 1:26
     inv_phos_rate(i) = x(i)/phos_rate(i);
     inv_phos_rate;
 end

 for i = 1:length(phos_rate)
     c1(i) = sqrt(7*(0.1/0.025)*(inv_phos_rate(i))^2);
     c2(i) = (((4*10^-4)*((10^-2)/(4.8*(10^-2)*4*(10^-2))))*(1+phos_rate(i)))^-1;
     c1;
     c2;
 end

 for j = 1:26
     syms DegU
     eqn = ((alpha*((c1(j))^2) + DegU^2)/((c1(j))^2 + DegU^2)) - (DegU)/(c2(j)) ==0;
     S(j) = solve(eqn, DegU, 'Real', true);
     S;
 end

 plot(phos_rate, S)
 
 

Could anybody explain what is going wrong?

Answer 1

[Sriram Tadavarty]

Hi Ellen,

The issue comes because for one of the equation, there are three roots, but till that iteration, only single root is present in S. To observe the different roots, you can make the following modifications

     S{j} = solve(eqn, DegU, 'Real', true); % Replace S(j) with S{j}
     S1(j) = S{j}(1);

Placing these lines in the code and then while plotting use S1 instead of S

plot(phos_rate, S1)

Look that S will have one of the roots as 3 x 1 and due to this the error.

Hope this helps.

Regards,

Sriram

[Ellen Brown]

Hi Sriram,

Now its coming up with an error

"Error using sym/subsasgn (line 942)

Invalid indexing assignment.

Error in main (line 48)

S{j} = solve(eqn, DegU, 'Real', true); % Replace S(j) with S{j}"

[Sriram Tadavarty]

Can you once clear the workspace and try?

[Ellen Brown]

That worked, thank you so much!!

Answer 2

[Yineth Fernanda Olaya Sedano]

Hi, my code has the following error:

Unable to perform assignment because the indices on the left side are not compatible with the size of

the right side.

Error in sym/privsubsasgn (line 1229)

L_tilde2 = builtin('subsasgn',L_tilde,struct('type','()','subs',{varargin}),R_tilde);

Error in sym/subsasgn (line 1060)

C = privsubsasgn(L,R,inds{:});

Error in aa (line 35)

Tdet(i) = solve ((-a(i)/X^2)+((D*h(i))/2)+ ...

My code is as follows:

clc ; clear ; close

format long

% REAPROVISIONAMIENTO CONJUNTO

a = xlsread('Ejemplo_numerico.xlsx','C6:C11') ; %Costo de pedir producto unid

h = xlsread('Ejemplo_numerico.xlsx','D6:D11') ; %Costo de matener inventario

D = xlsread('Ejemplo_numerico.xlsx','E6:E11') ; % Demanda

sg = xlsread('Ejemplo_numerico.xlsx','F6:F11') ; %Desviacion durante el tiempo de entrega

L = xlsread('Ejemplo_numerico.xlsx','G6:G11') ; %Duración del tiempo de entrega

B = xlsread('Ejemplo_numerico.xlsx','H6:H11') ; %Costo de pedido pendiente

A = xlsread('Ejemplo_numerico.xlsx','C12:C12') ; %Costo de pedir

M = xlsread('Ejemplo_numerico.xlsx','I6:I11') ; % Demanda promedio durante el tiempo de entrega

Y = xlsread('Ejemplo_numerico.xlsx','J6:J11') ; % Requerimiento de espacio del producto CT

bn = xlsread('Ejemplo_numerico.xlsx','C30:C30') ; %Costo fijo de almacenamento por adquirir el espacio Sn

cn = xlsread('Ejemplo_numerico.xlsx','C31:C31') ;% Costo variable de almacenamiento%

sn = xlsread('Ejemplo_numerico.xlsx','C29:C29') ;%Espacios de almacenamiento disponible%

%Y2 = xlsread('Ejemplo_numerico.xlsx','F19:F24') ; % Requerimiento de espacio del producto CO

%Q2 = xlsread('Ejemplo_numerico.xlsx','Q25:Q36') ; % Cantidad de pedido CO

%R = xlsread('Ejemplo_numerico.xlsx','S25:S36') ; % Punto de reorden en CO

Zalfha = (-1.3);

syms X;

n = length(a) ;

for i=1:n

Tdet1(i) = sqrt(2*a(i)/D(i)*h(i));

FZ(i) = 1-((Tdet1(i).*((cn.*Y(i))+h(i)))./(B(i))); %((cn.*Y(i).+h(i)).*(Tdet(i)./B(i))) ; % Acumulado

alfa(i) = 1-FZ(i) ; % Nivel de Servicio con Tdet

Z(i) = (norminv(1-alfa(i)/2)) ;

fz(i) = normpdf(Z(i)) ; %%abs(0.5-alfa(i)) ; % Función de densidad normal con Z(Tdet)

Tdet(i) = solve ((-a(i)/X^2)+((D*h(i))/2)+ ...

((Z(i)*sg(i))/(2*sqrt(X+L(i))))+ ...

(sg(i)*fz(i))*((((-B(i))*X^2)- ...

(2*X*B(i)*L(i)))/((2*X^3)*sqrt(X+L(i))))- ...

((sg(i)*Z(i))*(((2*L(i)-X)*(((X)*(cn(i)))*Y(i))+ ...

((X)*h(i))))/(2*sqrt(X+L(i))))+((((cn(i))*Y(i))*sqrt(X+L(i)))/X))== 0,X;

b(i) = sqrt ( Tdet(i) + L(i))* fz(i) ;

b_der_1(i) = fz(i)/(2*sqrt(Tdet(i)+L(i))) + sqrt(Tdet(i) + L(i))*Z(i)*((((cn.*Y(i))+h(i)))./(B(i))) ;

b_der_2(i) = ((Z(i).*((cn.*Y(i))+h(i)))./(B(i).*sqrt(Tdet(i) + L(i)))) - (fz(i))/(4*(Tdet(i)+L(i))^(3/2)) - ((sqrt(Tdet(i) + L(i))*(((cn.*Y(i))+h(i)))^(2))./(((B(i)^(2))*fz(i))));%((sqrt(Tdet(i) + L(i))*(cn.*Y(i)+h(i))^2)/((B(i)^2)*fz(i)));

u(i) = a(i) + B(i)*sg(i)*(b(i)-b_der_1(i)*Tdet(i)+b_der_2(i)*(Tdet(i)^2)/2);

v(i) = D(i)*h(i) + B(i)*sg(i)*b_der_2(i) ;

w(i) = B(i)*sg(i)*(b_der_1(i)-b_der_2(i)*Tdet(i)) ;

T_opt(i) = (sqrt((2*u(i))/v(i))) ;

TC_opt(i) = sqrt(2*u(i)*v(i)) + w(i) ;

Zreal(i) = (h(i)/B(i))*T_opt(i) ;

end

T_orden = sort(T_opt) ; % 'sort' Ordenar los elementos en orden creciente

for i = 1:n

Pos(i) =find(T_orden==T_opt(i)) ;

end

Tj = 0 ;

stop = 0 ;

i = 1 ;

while i <= n % && stop==0

u_orden(i) = (u(Pos(i))) ;

v_orden(i) = (v(Pos(i))) ;

Tj (i) = sqrt((2*(A + sum(u_orden) ))/(sum(v_orden))) ;

if i == 1 && Tj(i) < 0

alerta = 1 ;

else

if i>1 && Tj(i) > Tj(i - 1)

stop = i ;

end

end

i = i + 1 ; % Contador de iteración

end

% stop = n % por si no sirve

Ts = min(Tj) ; % T's

s = find(Ts==Tj) ; % Posicion del Ts

for m = 1 : s

ki(m) = 1 ;

end

for m = s+1 : n

ki(m) = 1 ;

cond1 = 0 ;

cond2 = 0 ;

cond = Tj(m)/ Ts ;

while cond1==0 && cond2==0

Band1 = sqrt((ki(m) - 1)*ki(m)) ;

Band2 = sqrt((ki(m) + 1)*ki(m)) ;

if Band1 <= cond

cond1 = 1 ;

if Band2 >= cond

cond2 = 1 ;

else

cond1 = 0 ;

ki(m) = ki(m) + 1 ;

end

else

ki(m) = ki(m) + 1 ;

end

end

end

SumUK= (sum(u./ki));

SumKV= (sum(ki.*v));

SumW = (sum(w)) ;

T = sqrt(2*(A + SumUK)/SumKV) ;

TC = A./T + SumUK./T +(T./2).*SumKV + SumW + bn + sum(sum(cn*(Y.*((D.*T)+(Z.*sg.*sqrt(T+L))))));

Q1 = (D.*(ki').*T);

costodepedir= A./T ;

costodemantenerinventario= (SumUK./T) +((T./2).*SumKV);

costodepedidopendiente=SumW ;

costofijodealmacenamiento=bn ;

costovariabledealmacenamiento= sum(sum(cn*(Y.*((D.*T)+(Z.*sg.*sqrt(T+L))))));

%uno=sum(sum((Y(i).*Q(i))));

%dos=sum(sum(Y(i).*Z(i).*sg(i)));

%tres=sum(sum(Y(i).*M(i)));

%cuatro=sum(sum(Y2(i).*Q2(i)));

%cinco=sum(sum(Y2(i).*R(i)));

%Respacio= sum(uno)+sum(dos)+sum(cuatro)+sum(cinco)-sum(tres)-Sn-Zalfha;

%Esp1= sum(uno)+sum(dos);

[Walter Roberson]

Answered at https://www.mathworks.com/matlabcentral/answers/1643055-hello-my-code-has-the-following-error#answer_888885