Error using sym/subs Too many input arguments. Error in mx_model (line 176) f = subs(f, cup,cu,0);

Hi all, I am new to Matlab and I am trying to run a code from (http://www.columbia.edu/~mu2166/book/rer/) mxn model.I encounter the following error:

"Error using sym/subs

Too many input arguments."

What might be the problem? Thanks very much in advance.

Error in mxn_model (line 177)

f = subs(f, cup,cu,0);

Below you can find the code. Thanks very much.

% mxn_model.m

% mxn_model.m computes a symbolic log-linear approximation to the function f:

% E_t f(yp,y,xp,x) =0.

% where, a p denotes next-period variables and

% the function f are the equilibrium conditions of the MXN model developed in chapter 8, entitled

% ``Nontradable Goods And The Real Exchange,'' of the textbook

% `Open Economy Macroeconomics' by M. Uribe and S. Schmitt-Grohe,

% Princeton University Press, 2017.

%

% Run this program only once or every time the structure of the model changes. No need to re-run it when parameter values change.

%

%Output: Analytical expressions for f and its first derivatives as well as x and y.

%

% The output is written to <filename>_num_eval.m which can then be run for numerical evaluations

%

% Calls: anal_deriv.m and anal_deriv_print2f.m

%

%© Martín Uribe and Stephanie Schmitt-Grohé, May 2015.

clear all

cesm =0

filename = 'mxn'; %a file with this name and suffix _num_eval.m is created at the end of this program and contains symbolic expression for the function f and its derivatives fx fy fxp fyp

syms OMEGAM OMEGAX SIGG PHIM PHIX PHINT BETTA DELTA ALFAM ALFAX RSTAR DBAR PSSI TOT OUTPUT TFPX TFPM TFPN

syms STD_EPS_A ETASHOCK RHO_TOT STD_TOT

syms OMEGAN CHITAU CHIM MUTN MUMX ALFAN

syms PM PX PN

syms c cp hm hmp h_x h_xp d dp im imp ix ixp km kmp kmfu kmfup kx kxp kxfu kxfup am amp ax axp px pxp pm pmp ym ymp yx yxp r rp wm wmp wx wxp ux uxp um ump m mp x xp la lap

syms tot totp tfp_x tfp_xp tfp_m tfp_mp tfp_n tfp_np output outputp tby tbyp ivv ivvp

syms hn hnp ivn ivnp kn knp wn wnp ptau ptaup un unp an anp yn ynp pn pnp atau ataup ataun knfu knfup

syms output_constant_prices output_constant_pricesp c_constant_prices c_constant_pricesp ivv_constant_prices ivv_constant_pricesp

%Utitlity function:

U =((c - hn^OMEGAN/OMEGAN - hm^OMEGAM/OMEGAM - h_x^OMEGAX/OMEGAX)^(1-SIGG)-1)/(1-SIGG);

if cesm==1

A = (CHIM * am^(1-1/MUMX ) + (1-CHIM) * ax^(1-1/MUMX))^(1/(1-1/MUMX));

else

A = am^CHIM*ax^(1-CHIM);

end

B = (CHITAU * atau^(1-1/MUTN ) + (1-CHITAU) * an^(1-1/MUTN))^(1/(1-1/MUTN));

%Equilibrium conditions. The symbols e1, e2, ... denote equation 1, equation2, ...

%U_1 = la

e1 = -la + diff(U, 'c');

%U_2/U_1 = wm

e2 = wm + diff(U, 'hm')/diff(U,'c');

%U_3/U1 = wx

e3 = [wx + diff(U, 'h_x')/diff(U,'c');wn + diff(U, 'hn')/diff(U,'c')];

%Euler d

e4 = -la*ptau + BETTA * (1+r) * lap*ptaup ;

%Euler km

e5 = -la *(1+ PHIM*(kmp-km)) + BETTA*lap* (ump + 1-DELTA + PHIM * (kmfup-kmp));

%Euler km

e6 = [-la *(1+ PHIX*(kxp-kx)) + BETTA*lap * (uxp + 1-DELTA + PHIX * (kxfup-kxp)); -la *(1+ PHINT*(knp-kn)) + BETTA*lap * (unp + 1-DELTA + PHINT * (knfup-knp))];

%Evolution kmp

e7 = -kmp + (1-DELTA)*km + im;

%Evolution kxp

e8 = [-kxp + (1-DELTA) *kx + ix; -knp + (1-DELTA) *kn + ivn];

%Final good aggregation

e9 = [-pm + ptau* diff(A, 'am'); -px + ptau*diff(A, 'ax')];

%Final good aggregation

e10 = [-ptau + diff(B, 'atau'); -pn + diff(B,'an')];

%Production of Importables

e11 = - tfp_m* km^ALFAM*hm^(1-ALFAM)+ ym ;

%Production of Importables

e12 = [- tfp_x* kx^ALFAX*h_x^(1-ALFAX)+ yx ; -tfp_n*kn^ALFAN*hn^(1-ALFAN)+ yn] ;

%Foc Firms capital

e13 = [-um + pm *tfp_m *ALFAM*km^(ALFAM-1)*hm^(1-ALFAM); -un + pn* tfp_n*ALFAN*kn^(ALFAN-1)*hn^(1-ALFAN)];

%Foc Firms labor

e14 = -ux + px *tfp_x *ALFAX*kx^(ALFAX-1)*h_x^(1-ALFAX);

%Foc Firms capital

e15 = [-wm + pm *tfp_m *(1-ALFAM)*km^ALFAM*hm^(-ALFAM); -wn + pn *tfp_n *(1-ALFAN)*kn^ALFAN*hn^(-ALFAN)];

%Foc Firms labor

e16 = -wx + px *tfp_x *(1-ALFAX)*kx^ALFAX*h_x^(-ALFAX);

% Market clearing for final goods:

e17 = - B + c + im +ix +ivn + PHIX/2*(kxp-kx)^2 + PHIM/2*(kmp-km)^2+PHINT/2*(knp-kn)^2;

%Imports at final goods prices

e18 = [pm*(-am+ym) + m; ; -A + atau; an - yn];

%Exports at final good prices

e19 = px*(-ax+yx) -x;

%Evolution of foreign debt

e20 = -ptau*d - m + ptau*dp /(1+r) + x;

%Country premium

e21 = -r + RSTAR + PSSI * (exp(dp-DBAR) -1);

%Definition of Tot

e22 = -tot + px / pm;

%Evolution of TOT

e23 = [-log(totp/TOT) + RHO_TOT * log(tot/TOT);

-log(tfp_xp/TFPX) + RHO_TOT * log(tfp_x/TFPX);

-log(tfp_mp/TFPM) + RHO_TOT * log(tfp_m/TFPM);

-log(tfp_np/TFPN) + RHO_TOT * log(tfp_n/TFPN);

];

%make kfu=kp

e24 = [-kxfu+kxp; -kmfu + kmp; -knfu + knp];

%definition of output in terms of final goods and output at constant prices

e25 = [-output+px*yx+pm*ym+pn*yn;

-ivv+im+ix+ivn;

-output_constant_prices+PX*yx+PM*ym+PN*yn;

-c_constant_prices+c/output*output_constant_prices;

-ivv_constant_prices+ivv/output*output_constant_prices];

%trade balance in final goods relative to steady state output

e26 = -tby + (x/output-m/output)*output_constant_prices/OUTPUT;

%Create function f

f = eval(eval([e1;e2;e3;e4;e5;e6;e7;e8;e9;e10;e11;e12;e13;e14;e15;e16;e17;e18;e19;e20;e21;e22;e23;e24; e25; e26]));

% Define the vector of controls in periods t and t+1, controlvar and controlvarp, and the vector of states in periods t and t+1, statevar and statevarp

%States to substitute from levels to logs

states_in_logs = [ km kx kn tfp_m tfp_x tfp_n tot];

states_in_logsp = [ kmp kxp knp tfp_mp tfp_xp tfp_np totp];

statevar = [d states_in_logs];

statevarp = [dp states_in_logsp];

controls_in_logs = [c hm h_x hn im ix ivn am ax an atau px pm pn ptau ym yx yn wm wx wn ux um un m x output la kmfu kxfu knfu ivv output_constant_prices c_constant_prices ivv_constant_prices];

controls_in_logsp = [cp hmp h_xp hnp imp ixp ivnp amp axp anp ataup pxp pmp pnp ptaup ymp yxp ynp wmp wxp wnp uxp ump unp mp xp outputp lap kmfup kxfup knfup ivvp output_constant_pricesp c_constant_pricesp ivv_constant_pricesp];

controlvar = [controls_in_logs tby r];

controlvarp = [controls_in_logsp tbyp rp];

%Number of states

nstate = length(statevar);

%Make f a function of the logarithm of the state and control vector

%variables to substitute from levels to logs

variables_in_logs = transpose([states_in_logs, controls_in_logs, states_in_logsp, controls_in_logsp]);

f = subs(f, variables_in_logs, exp(variables_in_logs));

approx = 1;

%Compute analytical derivatives of f

[fx,fxp,fy,fyp]=anal_deriv(f,statevar,controlvar,statevarp,controlvarp,approx);

%Make f and its derivatives a function of the level of its arguments rather than the log

f = subs(f, variables_in_logs, log(variables_in_logs));

fx = subs(fx, variables_in_logs, log(variables_in_logs));

fy = subs(fy, variables_in_logs, log(variables_in_logs));

fxp = subs(fxp, variables_in_logs, log(variables_in_logs));

fyp = subs(fyp, variables_in_logs, log(variables_in_logs));

%Symbolically evaluate f and its derivatives at the nonstochastic steady state (c=cp, etc.)

cu = transpose([statevar controlvar km kx kn ]);

cup = transpose([statevarp controlvarp kmfu kxfu knfu ]);

for subcb=1:2 %substitution must be run twice in case the original system is a stochastic difference equation of order higher than one. For example, the current model features k_t, k_t+1, and k_t+2 and thus is a 2nd order difference equation

f = subs(f, cup,cu,0);

fx = subs(fx, cup,cu,0);

fy = subs(fy, cup,cu,0);

fxp = subs(fxp, cup,cu,0);

fyp = subs(fyp, cup,cu,0);

end

%Construct ETASHOCK matrix, which determines the var/cov of the forcing term of the system. Specifically, the state vector evolves over time according to

%x_t+1 = hx x_t + ETASHOCK epsilon_t+1

ETASHOCK(nstate,1) = STD_TOT;

ETASHOCK(1:nstate-1) = 0;

varshock = ETASHOCK*ETASHOCK';

%Print derivatives to file <filename>_num_eval.m' for model evaluation

anal_deriv_print2f(filename,fx,fxp,fy,fyp,f,ETASHOCK);

ncontrol = length(controlvar);

%Positions of variables in state and control vectors

for i=1:ncontrol

eval(['n' char(controlvar(i)) ' = ' num2str(i)]);

end

for i=1:nstate

eval(['n' char(statevar(i)) ' = ' num2str(i)]);

end

eval(['save ' filename '.mat'])

Answer 1

[Stephan]

Hi,

as the error message says, there are too much input arguments. The correct syntax for subs is:

subs(eqn,old,new)

The code you are using has 4 input arguments, which is one more then allowed.

Best regards

Stephan

[Paul Bousquet]

https://www.mathworks.com/matlabcentral/answers/339791-too-many-input-arguments-with-sym-function#comment_453145

Answer 2

[Steven Lord]

In the past the subs function for symbolic expressions did accept four inputs. The last input controlled whether or not we tried substituting in the reverse order subs(expression, new, old) when substituting in the expected order subs(expression, old, new) didn't change the result of the expression. This was for backwards compatibility. I think we had been warning about that syntax being deprecated for a while (at least a couple years) before it was finally removed several years ago.