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<a name="Initial-and-terminal-conditions"></a>
<div class="header">
<p>
Next: <a href="Shocks-on-exogenous-variables.html#Shocks-on-exogenous-variables" accesskey="n" rel="next">Shocks on exogenous variables</a>, Previous: <a href="Auxiliary-variables.html#Auxiliary-variables" accesskey="p" rel="prev">Auxiliary variables</a>, Up: <a href="The-Model-file.html#The-Model-file" accesskey="u" rel="up">The Model file</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Command-and-Function-Index.html#Command-and-Function-Index" title="Index" rel="index">Index</a>]</p>
</div>
<a name="Initial-and-terminal-conditions-1"></a>
<h3 class="section">4.7 Initial and terminal conditions</h3>

<p>For most simulation exercises, it is necessary to provide initial (and
possibly terminal) conditions. It is also necessary to provide initial
guess values for non-linear solvers. This section describes the
statements used for those purposes.
</p>
<p>In many contexts (deterministic or stochastic), it is necessary to
compute the steady state of a non-linear model: <code>initval</code> then
specifies numerical initial values for the non-linear solver. The
command <code>resid</code> can be used to compute the equation residuals for
the given initial values.
</p>
<p>Used in perfect foresight mode, the types of forward-looking models for
which Dynare was designed require both initial and terminal
conditions. Most often these initial and terminal conditions are
static equilibria, but not necessarily.
</p>
<p>One typical application is to consider an economy at the equilibrium at time 0,
trigger a shock in first period, and study the trajectory of return to
the initial equilibrium. To do that, one needs <code>initval</code> and
<code>shocks</code> (see <a href="Shocks-on-exogenous-variables.html#Shocks-on-exogenous-variables">Shocks on exogenous variables</a>).
</p>
<p>Another one is to study, how an economy, starting from arbitrary
initial conditions at time 0 converges toward equilibrium. 
In this case models, the command <code>histval</code> permits to specify different 
historical initial values for variables with lags for the 
periods before the beginning of the simulation. Due to the design of Dynare, 
in this case <code>initval</code> is used to specify the terminal conditions.
</p>

<dl>
<dt><a name="index-initval"></a>Block: <strong>initval</strong> <em>;</em></dt>
<dt><a name="index-initval-1"></a>Block: <strong>initval</strong> <em>(<var>OPTIONS</var>&hellip;);</em></dt>
<dd>
<p><em>Description</em>
</p>
<p>The <code>initval</code> block has two main purposes: providing guess values 
for non-linear solvers in the context of perfect foresight simulations 
and providing guess values for steady state computations in both perfect 
foresight and stochastic simulations. Depending on the presence of <code>histval</code> 
and <code>endval</code>-blocks it is also used for declaring the initial and 
terminal conditions in a perfect foresight simulation exercise. 
Because of this interaction of the meaning of an <code>initval</code>-block 
with the presence of <code>histval</code> and <code>endval</code>-blocks in perfect foresight 
simulations, it is strongly recommended to check that the 
constructed <code>oo_.endo_simul</code> and <code>oo_.exo_simul</code> variables 
contain the desired values after running <code>perfect_foresight_setup</code> 
and before running <code>perfect_foresight_solver</code>. In the presence of leads 
and lags, these subfields of the results structure will store the historical 
values for the lags in the first 
column/row and the terminal values for the leads in the last column/row.
</p>
<p>The <code>initval</code> block is terminated by <code>end;</code>, and contains lines of the
form:
</p><div class="example">
<pre class="example"><var>VARIABLE_NAME</var> = <var>EXPRESSION</var>;
</pre></div>

<p><em>In a deterministic (<i>i.e.</i> perfect foresight) model</em>
</p>
<p>First, it will fill both the <code>oo_.endo_simul</code> and <code>oo_.exo_simul</code> variables 
storing the endogenous and exogenous variables with the values provided by this block. 
If there are no other blocks present, it will therefore provide the initial and 
terminal conditions for all the endogenous and exogenous variables, because it 
will also fill the last column/row of these matrices. For the intermediate simulation periods 
it thereby provides the starting values for the solver.
In the presence of a <code>histval</code> block (and therefore absence of an <code>endval</code>-block), 
this <code>histval</code> block will provide/overwrite the historical values for the state variables (lags) by 
setting the first column/row of <code>oo_.endo_simul</code> and <code>oo_.exo_simul</code>. 
This implies that the <code>initval</code>-block in the presence of <code>histval</code> only sets the terminal values 
for the variables with leads and provides initial values for the perfect foresight solver.
</p>

<p>Because of these various functions of <code>initval</code> it is often necessary to provide values for all the
endogenous variables in an <code>initval</code> block. Initial and terminal conditions are strictly 
necessary for lagged/leaded variables, while feasible starting values are required for the solver. 
It is important to be aware that if some variables, endogenous or exogenous, are not mentioned in the
<code>initval</code> block, a zero value is assumed. It is particularly important to keep 
this in mind when specifying exogenous variables using <code>varexo</code> that are not allowed 
to take on the value of zero, like <i>e.g.</i> TFP.
</p>
<p>Note that if the <code>initval</code> block is immediately followed by a
<code>steady</code> command, its semantics are slightly changed. 
The <code>steady</code> command will compute the steady state of the model for all the 
endogenous variables, assuming that exogenous variables are kept constant at the value 
declared in the <code>initval</code> block. These steady state values conditional on 
the declared exogenous variables are then written into <code>oo_.endo_simul</code> and take up the 
potential roles as historical and terminal conditions as well 
as starting values for the solver. An <code>initval</code> block followed by <code>steady</code>
is therefore formally equivalent to an <code>initval</code> block with the specified values
for the exogenous variables, and the endogenous variables set to the associated steady state values
conditional on the exogenous variables.
</p>
<p><em>In a stochastic model</em>
</p>
<p>The main purpose of <code>initval</code> is to provide initial guess values
for the non-linear solver in the steady state computation. Note that
if the <code>initval</code> block is not followed by <code>steady</code>, the
steady state computation will still be triggered by subsequent
commands (<code>stoch_simul</code>, <code>estimation</code>&hellip;).
</p>
<p>It is not necessary to declare <code>0</code> as initial value for exogenous
stochastic variables, since it is the only possible value.
</p>
<p>The subsequently computed steady state (not the initial values, use
<a href="#histval">histval</a> for this) will be used as the initial condition at all
the periods preceeding the first simulation period for the three
possible types of simulations in stochastic mode:
</p>
<ul>
<li> <a href="Stochastic-solution-and-simulation.html#stoch_005fsimul">stoch_simul</a>, if the <code>periods</code> option is specified

</li><li> <a href="Estimation.html#forecast">forecast</a> as the initial point at which the forecasts are computed

</li><li> <a href="Forecasting.html#conditional_005fforecast">conditional_forecast</a> as the initial point at which the conditional forecasts are computed
</li></ul>

<p>To start simulations at a particular set of starting values that are not a computed steady state, use <a href="#histval">histval</a>.
</p>
<p><em>Options</em>
</p>
<dl compact="compact">
<dt><code>all_values_required</code></dt>
<dd><a name="all_005fvalues_005frequired"></a><p>Issues an error and stops processing the <samp>.mod</samp> file if there is at least
one endogenous or exogenous variable that has not been set in the <code>initval</code>
block.
</p></dd>
</dl>

<p><em>Example</em>
</p>
<div class="example">
<pre class="example">initval;
c = 1.2;
k = 12;
x = 1;
end;

steady;
</pre></div>

</dd></dl>

<dl>
<dt><a name="index-endval"></a>Block: <strong>endval</strong> <em>;</em></dt>
<dt><a name="index-endval-1"></a>Block: <strong>endval</strong> <em>(<var>OPTIONS</var>&hellip;);</em></dt>
<dd>
<p><em>Description</em>
</p>
<p>This block is terminated by <code>end;</code>, and contains lines of the
form:
</p><div class="example">
<pre class="example"><var>VARIABLE_NAME</var> = <var>EXPRESSION</var>;
</pre></div>

<p>The <code>endval</code> block makes only sense in a deterministic model and cannot 
be used together with <code>histval</code>. Similar to the <code>initval</code> command, 
it will fill both the <code>oo_.endo_simul</code> and <code>oo_.exo_simul</code> variables 
storing the endogenous and exogenous variables with the values provided by this block. 
If no <code>initval</code>-block is present, it will fill the whole matrices, therefore 
providing the initial and terminal conditions for all the endogenous and exogenous 
variables, because it will also fill the first and last column/row of these matrices. Due to
also filling the intermediate simulation periods it will provide the starting values for the solver as well.
</p>
<p>If an <code>initval</code>-block is present, <code>initval</code> will provide the historical 
values for the variables (if there are states/lags), while <code>endval</code> will fill 
the remainder of the matrices, thereby still providing i) the terminal conditions 
for variables entering the model with a lead and ii) the initial guess values 
for all endogenous variables at all the simulation dates for the perfect foresight solver.
</p>
<p>Note that if some variables, endogenous or exogenous, are NOT mentioned in the
<code>endval</code> block, the value assumed is that of the last
<code>initval</code> block or <code>steady</code> command (if present). Therefore, 
in contrast to <code>initval</code>, omitted variables are not automatically assumed to be 0 
in this case. Again, it is strongly recommended to check the 
constructed <code>oo_.endo_simul</code> and <code>oo_.exo_simul</code> variables 
after running <code>perfect_foresight_setup</code> and before running <code>perfect_foresight_solver</code>
to see whether the desired outcome has been achieved. 
</p>
<p>Like <code>initval</code>, if the <code>endval</code> block is immediately followed by a
<code>steady</code> command, its semantics are slightly changed. 
The <code>steady</code> command will compute the steady state of the model for all 
the endogenous variables, assuming that exogenous variables are kept constant 
to the value declared in the <code>endval</code> block. These steady state values 
conditional on the declared exogenous variables are then written into <code>oo_.endo_simul</code> 
and therefore take up the potential roles as historical and terminal conditions 
as well as starting values for the solver. An <code>endval</code> block followed by <code>steady</code>
is therefore formally equivalent to an <code>endval</code> block with the specified values
for the exogenous variables, and the endogenous variables set to the associated steady state values.
</p>
<p><em>Options</em>
</p>
<dl compact="compact">
<dt><code>all_values_required</code></dt>
<dd><p>See <a href="#all_005fvalues_005frequired">all_values_required</a>.
</p></dd>
</dl>

<p><em>Example</em>
</p>
<div class="example">
<pre class="example">var c k;
varexo x;
&hellip;
initval;
c = 1.2;
k = 12;
x = 1;
end;

steady;

endval;
c = 2;
k = 20;
x = 2;
end;

steady;
</pre></div>

<p>The initial equilibrium is computed by <code>steady</code> conditional on <code>x=1</code>,
and the terminal one conditional on <code>x=2</code>. The <code>initval</code>-block sets 
the initial condition for <code>k</code>, while the <code>endval</code>-block sets the terminal
condition for <code>c</code>. The starting values for the perfect foresight solver are 
given by the <code>endval</code>-block. A detailed explanation follows below the next example.
</p>
<p><em>Example</em>
</p>
<div class="example">
<pre class="example">var c k;
varexo x;
&hellip;
model;
c + k - aa*x*k(-1)^alph - (1-delt)*k(-1);
c^(-gam) - (1+bet)^(-1)*(aa*alph*x(+1)*k^(alph-1) + 1 - delt)*c(+1)^(-gam);
end;

initval;
k = 12;
end;

endval;
c = 2;
x = 1.1;
end;
simul(periods=200);

</pre></div>

<p>In this example, the problem is finding the optimal path for consumption and
capital for the periods <SPAN CLASS="MATH"><IMG
 WIDTH="39" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_12.png"
 ALT="$t=1$"></SPAN> to <SPAN CLASS="MATH"><IMG
 WIDTH="61" HEIGHT="15" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_13.png"
 ALT="$T=200$"></SPAN>, given the path of the exogenous
technology level <code>x</code>. <code>c</code> is a forward looking variable and the
exogenous variable <code>x</code> appears with a lead in the expected return of
physical capital, so we need terminal conditions for them, while <code>k</code> is a
purely backward-looking (state) variable, so we need an initial condition for
it.
</p>
<p>Setting <code>x=1.1</code> in the <code>endval</code>-block without a <code>shocks</code>-block implies that technology
is at <SPAN CLASS="MATH"><IMG
 WIDTH="25" HEIGHT="13" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_14.png"
 ALT="$1.1$"></SPAN> in <SPAN CLASS="MATH"><IMG
 WIDTH="39" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_12.png"
 ALT="$t=1$"></SPAN> and stays there forever, because <code>endval</code>
is filling all entries of <code>oo_.endo_simul</code> and <code>oo_.exo_simul</code> except 
for the very first one, which stores the initial conditions and was set to <SPAN CLASS="MATH"><IMG
 WIDTH="12" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_2.png"
 ALT="$0$"></SPAN> by the <code>initval</code>-block when not 
explicitly specifying a value for it. 
</p>
<p>Because the law of motion for capital is backward-looking, we need an initial
condition for <code>k</code> at time <SPAN CLASS="MATH"><IMG
 WIDTH="12" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_2.png"
 ALT="$0$"></SPAN>. Due to the presence of <code>endval</code>, this cannot be 
done via a <code>histval</code>-block, but rather must be specified in the <code>initval</code>-block.
Similarly, because the Euler equation is forward-looking, we need a
terminal condition for <code>c</code> at <SPAN CLASS="MATH"><IMG
 WIDTH="55" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_15.png"
 ALT="$t=201$"></SPAN>, which is specified in the
<code>endval</code>-block. 
</p>
<p>As can be seen, it is not necessary to specify <code>c</code> and <code>x</code> in the <code>initval</code>-block and
<code>k</code> in the <code>endval</code>-block, because they have no impact on the results. Due to 
the optimization problem in the first period being to choose <code>c,k</code>
at <SPAN CLASS="MATH"><IMG
 WIDTH="39" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_12.png"
 ALT="$t=1$"></SPAN> given the predetermined capital stock <code>k</code> inherited from <SPAN CLASS="MATH"><IMG
 WIDTH="39" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_16.png"
 ALT="$t=0$"></SPAN> as
well as the current and future values for technology <code>x</code>, the values for
<code>c</code> and <code>x</code> at time <SPAN CLASS="MATH"><IMG
 WIDTH="39" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_16.png"
 ALT="$t=0$"></SPAN> play no role. The same applies to the choice of
<code>c,k</code> at time <SPAN CLASS="MATH"><IMG
 WIDTH="55" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_17.png"
 ALT="$t=200$"></SPAN>, which does not depend on <code>k</code> at <SPAN CLASS="MATH"><IMG
 WIDTH="55" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_15.png"
 ALT="$t=201$"></SPAN>. As
the Euler equation shows, that choice only depends on current capital as
well as future consumption <code>c</code> and technology <code>x</code>, but not on
future capital <code>k</code>. The intuitive reason is that those variables are
the consequence of optimization problems taking place in at periods <SPAN CLASS="MATH"><IMG
 WIDTH="39" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_16.png"
 ALT="$t=0$"></SPAN>
and <SPAN CLASS="MATH"><IMG
 WIDTH="55" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_15.png"
 ALT="$t=201$"></SPAN>, respectively, which are not modeled here.
</p>
<p><em>Example</em>
</p>
<div class="example">
<pre class="example">initval;
c = 1.2;
k = 12;
x = 1;
end;

endval;
c = 2;
k = 20;
x = 1.1;
end;
</pre></div>

<p>In this example, initial conditions for the forward-looking variables <code>x</code>
and <code>c</code> are provided, together with a terminal condition for the backward-looking
variable <code>k</code>. As shown in the previous example, these values will not affect the simulation 
results. Dynare simply takes them as given and basically assumes that there were realizations
of exogenous variables and states that make those choices
equilibrium values (basically initial/terminal conditions
at the unspecified time periods <SPAN CLASS="MATH"><IMG
 WIDTH="39" HEIGHT="30" ALIGN="MIDDLE" BORDER="0"
 SRC="dynare.html_18.png"
 ALT="$t&lt;0$"></SPAN> and <SPAN CLASS="MATH"><IMG
 WIDTH="55" HEIGHT="30" ALIGN="MIDDLE" BORDER="0"
 SRC="dynare.html_19.png"
 ALT="$t&gt;201$"></SPAN>).
</p> 
<p>The above example suggests another way of looking at the use of <code>steady</code>
after <code>initval</code> and <code>endval</code>. Instead of saying that the
implicit unspecified conditions before and after the simulation range
have to fit the initial/terminal conditions of the endogenous variables
in those blocks, <code>steady</code> specifies that those conditions at <SPAN CLASS="MATH"><IMG
 WIDTH="39" HEIGHT="30" ALIGN="MIDDLE" BORDER="0"
 SRC="dynare.html_18.png"
 ALT="$t&lt;0$"></SPAN> and
<SPAN CLASS="MATH"><IMG
 WIDTH="55" HEIGHT="30" ALIGN="MIDDLE" BORDER="0"
 SRC="dynare.html_19.png"
 ALT="$t&gt;201$"></SPAN> are equal to being at the steady state given the exogenous
variables in the <code>initval</code> and <code>endval</code>-blocks. The
endogenous variables at <SPAN CLASS="MATH"><IMG
 WIDTH="39" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_16.png"
 ALT="$t=0$"></SPAN> and <SPAN CLASS="MATH"><IMG
 WIDTH="55" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_15.png"
 ALT="$t=201$"></SPAN> are then set to the corresponding steady state
equilibrium values.
</p> 
<p>The fact that <code>c</code> at <SPAN CLASS="MATH"><IMG
 WIDTH="39" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_16.png"
 ALT="$t=0$"></SPAN> and <code>k</code> at <SPAN CLASS="MATH"><IMG
 WIDTH="55" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_15.png"
 ALT="$t=201$"></SPAN> specified in
<code>initval</code> and <code>endval</code> are taken as given has an important
implication for plotting the simulated vector for the endogenous
variables, <i>i.e.</i> the rows of <code>oo_.endo_simul</code>: this vector will
also contain the initial and terminal
conditions and thus is 202 periods long in the example. When you specify
arbitrary values for the initial and terminal conditions for forward- and
backward-looking variables, respectively, these values can be very far
away from the endogenously determined values at <SPAN CLASS="MATH"><IMG
 WIDTH="39" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_12.png"
 ALT="$t=1$"></SPAN> and <SPAN CLASS="MATH"><IMG
 WIDTH="55" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_17.png"
 ALT="$t=200$"></SPAN>. While the
values at <SPAN CLASS="MATH"><IMG
 WIDTH="39" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_16.png"
 ALT="$t=0$"></SPAN> and <SPAN CLASS="MATH"><IMG
 WIDTH="55" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_15.png"
 ALT="$t=201$"></SPAN> are unrelated to the dynamics for <SPAN CLASS="MATH"><IMG
 WIDTH="85" HEIGHT="30" ALIGN="MIDDLE" BORDER="0"
 SRC="dynare.html_20.png"
 ALT="$0&lt;t&lt;201$"></SPAN>, they
may result in strange-looking large jumps. In the example above,
consumption will display a large jump from <SPAN CLASS="MATH"><IMG
 WIDTH="39" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_16.png"
 ALT="$t=0$"></SPAN> to <SPAN CLASS="MATH"><IMG
 WIDTH="39" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_12.png"
 ALT="$t=1$"></SPAN> and capital will
jump from <SPAN CLASS="MATH"><IMG
 WIDTH="55" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_17.png"
 ALT="$t=200$"></SPAN> to <SPAN CLASS="MATH"><IMG
 WIDTH="55" HEIGHT="14" ALIGN="BOTTOM" BORDER="0"
 SRC="dynare.html_15.png"
 ALT="$t=201$"></SPAN> when using <a href="Displaying-and-saving-results.html#rplot">rplot</a> or manually plotting <code>oo_.endo_val</code>.
</p>
</dd></dl>

<dl>
<dt><a name="index-histval"></a>Block: <strong>histval</strong> <em>;</em></dt>
<dt><a name="index-histval-1"></a>Block: <strong>histval</strong> <em>(<var>OPTIONS</var>&hellip;);</em></dt>
<dd><a name="histval"></a><p><em>Description</em>
</p>
<p><em>In a deterministic perfect foresight context</em>
</p>
<p>In models with lags on more than one period, the <code>histval</code> block
permits to specify different historical initial values for different
periods of the state variables. In this case, the <code>initval</code>-block takes over the role of specifying 
terminal conditions and starting values for the solver. Note that the <code>histval</code> block does not 
take non-state variables.   
</p>
<p>This block is terminated by <code>end;</code>, and contains lines of the
form:
</p><div class="example">
<pre class="example"><var>VARIABLE_NAME</var>(<var>INTEGER</var>) = <var>EXPRESSION</var>;
</pre></div>

<p><var>EXPRESSION</var> is any valid expression returning a numerical value
and can contain already initialized variable names.
</p>
<p>By convention in Dynare, period 1 is the first period of the
simulation. Going backward in time, the first period before the start
of the simulation is period <code>0</code>, then period <code>-1</code>, and so on.
</p>
<p>State variables not initialized in the <code>histval</code> block are assumed to
have a value of zero at period 0 and before. Note that <code>histval</code>
cannot be followed by <code>steady</code>.
</p>
<p><em>Example</em>
</p><div class="example">
<pre class="example">model;
x=1.5*x(-1)-0.6*x(-2)+epsilon;
log(c)=0.5*x+0.5*log(c(+1));
end;

histval;
x(0)=-1;
x(-1)=0.2;
end;

initval;
c=1;
x=1;
end;
</pre></div>

<p>In this example, <code>histval</code> is used to set the historical conditions for the two lags
of the endogenous variable <code>x</code>, stored in the first column of <code>oo_.endo_simul</code>. 
The <code>initval</code> block is used to set the terminal condition for the forward looking variable <code>c</code>,
stored in the last column of <code>oo_.endo_simul</code>. Moreover, the <code>initval</code> block defines
the starting values for the perfect foresight solver for both endogenous variables <code>c</code> and <code>x</code>.
</p>
<p><em>In a stochastic simulation context</em>
</p>
<p>In the context of stochastic simulations, <code>histval</code> allows setting
the starting point of those simulations in the state space. As for the case of
perfect foresight simulations, all not explicitly specified variables are set to 0.
Moreover, as only states enter the recursive policy functions, all values specified for control variables will be ignored. This can be used
</p>
<ul>
<li> in <a href="Stochastic-solution-and-simulation.html#stoch_005fsimul">stoch_simul</a>, if the <code>periods</code> option is specified. Note that this
only affects the starting point for the simulation, but not for the impulse
response functions. When using the <a href="Estimation.html#loglinear">loglinear</a> option, the
<code>histval</code>-block nevertheless takes the unlogged starting values.

</li><li> in <a href="Estimation.html#forecast">forecast</a> as the initial point at which the forecasts are computed. When using the <a href="Estimation.html#loglinear">loglinear</a> option, 
the <code>histval</code>-block nevertheless takes the unlogged starting values.

</li><li> in <a href="Forecasting.html#conditional_005fforecast">conditional_forecast</a> for a calibrated model as the initial point at which the conditional forecasts are computed.
When using the <a href="Estimation.html#loglinear">loglinear</a> option, the <code>histval</code>-block nevertheless takes the unlogged starting values.

</li><li> in <a href="Optimal-policy.html#Ramsey">Ramsey</a> policy, where it also specifies the values of the endogenous states at 
which the objective function of the planner is computed. Note that the initial values 
of the Lagrange multipliers associated with the planner&rsquo;s problem cannot be set
(see <a href="Optimal-policy.html#planner_005fobjective_005fvalue">planner_objective_value</a>).

</li></ul>

<p><em>Options</em>
</p>
<dl compact="compact">
<dt><code>all_values_required</code></dt>
<dd><p>See <a href="#all_005fvalues_005frequired">all_values_required</a>.
</p></dd>
</dl>


<p><em>Example</em>
</p>
<div class="example">
<pre class="example">var x y;
varexo e;

model;
x = y(-1)^alpha*y(-2)^(1-alpha)+e;
&hellip;
end;

initval;
x = 1;
y = 1;
e = 0.5;
end;

steady;

histval;
y(0) = 1.1;
y(-1) = 0.9;
end;

stoch_simul(periods=100);
</pre></div>

</dd></dl>

<dl>
<dt><a name="index-resid"></a>Command: <strong>resid</strong> <em>;</em></dt>
<dd>
<p>This command will display the residuals of the static equations of the
model, using the values given for the endogenous in the last
<code>initval</code> or <code>endval</code> block (or the steady state file if you
provided one, see <a href="Steady-state.html#Steady-state">Steady state</a>).
</p>
</dd></dl>


<dl>
<dt><a name="index-initval_005ffile"></a>Command: <strong>initval_file</strong> <em>(filename = <var>FILENAME</var>);</em></dt>
<dd>
<p><em>Description</em>
</p>
<p>In a deterministic setup, this command is used to specify a path for
all endogenous and exogenous variables. The length of these paths must
be equal to the number of simulation periods, plus the number of leads
and the number of lags of the model (for example, with 50 simulation
periods, in a model with 2 lags and 1 lead, the paths must have a
length of 53). Note that these paths cover two different things:
</p>
<ul>
<li> the constraints of the problem, which are given by the path for
exogenous and the initial and terminal values for endogenous

</li><li> the initial guess for the non-linear solver, which is given by the
path for endogenous variables for the simulation periods (excluding
initial and terminal conditions)
</li></ul>

<p>The command accepts three file formats:
</p>
<ul>
<li> M-file (extension <samp>.m</samp>): for each endogenous and exogenous
variable, the file must contain a row or column vector of the same name. Their length must be <code>periods+M_.maximum_lag+M_.maximum_lead</code> 

</li><li> MAT-file (extension <samp>.mat</samp>): same as for M-files.

</li><li> Excel file (extension <samp>.xls</samp> or <samp>.xlsx</samp>): for each endogenous and
exogenous, the file must contain a column of the same name. NB: Octave only
supports the <samp>.xlsx</samp> file extension and must have the
<a href="http://octave.sourceforge.net/io/">io</a> package installed (easily done via octave by typing &lsquo;<code>pkg install -forge io</code>&rsquo;).
</li></ul>

<p><em>Warning</em>
</p>
<p>The extension must be omitted in the command argument. Dynare will
automatically figure out the extension and select the appropriate file
type.
</p>
</dd></dl>

<dl>
<dt><a name="index-histval_005ffile"></a>Command: <strong>histval_file</strong> <em>(filename = <var>FILENAME</var>);</em></dt>
<dd>
<p>This command is equivalent to <code>histval</code>, except that it reads its input
from a file.
</p>
<p>This command is typically used in conjunction with <code>smoother2histval</code>.
</p>
</dd></dl>

<hr>
<div class="header">
<p>
Next: <a href="Shocks-on-exogenous-variables.html#Shocks-on-exogenous-variables" accesskey="n" rel="next">Shocks on exogenous variables</a>, Previous: <a href="Auxiliary-variables.html#Auxiliary-variables" accesskey="p" rel="prev">Auxiliary variables</a>, Up: <a href="The-Model-file.html#The-Model-file" accesskey="u" rel="up">The Model file</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Command-and-Function-Index.html#Command-and-Function-Index" title="Index" rel="index">Index</a>]</p>
</div>



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