Tutorials > Tutorial 7: A continuous model

// tutorial7.cpp

// Tutorial7 creates a network with three equation-based nodes

// performs the inference, then saves the model to disk.

#include "smile.h"

#include <cstdio>

static int CreateEquationNode(

DSL_network &net, const char *id, const char *name,

const char *equation, double loBound, double hiBound,

int xPos, int yPos);

static void UpdateAndShowStats(DSL_network &net);

static void SetUniformIntervals(DSL_network &net, int nodeHandle, int count);

int Tutorial7()

{

printf("Starting Tutorial7...\n");

DSL_errorH().RedirectToFile(stdout);

DSL_network net;

net.EnableRejectOutlierSamples(true);

int tra = CreateEquationNode(net,

"tra", "Return Air Temperature",

"tra=24", 23.9, 24.1,

280, 100);

int u_d = CreateEquationNode(net,

"u_d", "Damper Control Signal",

"u_d = Bernoulli(0.539)*0.8 + 0.2", 0, 1,

160, 100);

int toa = CreateEquationNode(net,

"toa", "Outside Air Temperature",

"toa=Normal(11,15)", -10, 40,

60, 100);

int tma = CreateEquationNode(net,

"tma", "Mixed Air Temperature",

"tma=toa*u_d+(tra-tra*u_d)", 10, 30,

110, 200);

SetUniformIntervals(net, toa, 5);

SetUniformIntervals(net, tma, 4);

printf("Results with no evidence:\n");

UpdateAndShowStats(net);

net.GetNode(toa)->Val()->SetEvidence(28.5);

printf("Results with outside air temperature set to 28.5:\n");

UpdateAndShowStats(net);

net.GetNode(toa)->Val()->ClearEvidence();

printf("Results with mixed air temperature set to 21:\n");

net.GetNode(tma)->Val()->SetEvidence(21.0); // ensure it's a double value

UpdateAndShowStats(net);

int res = net.WriteFile("tutorial7.xdsl");

if (DSL_OKAY != res)

{

return res;

}

printf("Tutorial7 complete: Network written to tutorial7.xdsl\n");

return DSL_OKAY;

}

static int CreateEquationNode(

DSL_network &net, const char *id, const char *name,

const char *equation, double loBound, double hiBound,

int xPos, int yPos)

{

int handle = net.AddNode(DSL_EQUATION, id);

DSL_node *node = net.GetNode(handle);

node->SetName(name);

auto eq = node->Def<DSL_equation>();

eq->SetEquation(equation);

eq->SetBounds(loBound, hiBound);

DSL_rectangle &position = node->Info().Screen().position;

position.center_X = xPos;

position.center_Y = yPos;

position.width = 85;

position.height = 55;

return handle;

}

static void ShowStats(DSL_network &net, int nodeHandle)

{

DSL_node* node = net.GetNode(nodeHandle);

const char *nodeId = node->GetId();

auto eqVal = node->Val<DSL_equationEvaluation>();

if (eqVal->IsEvidence())

{

double v;

eqVal->GetEvidence(v);

printf("%s has evidence set (%g)\n", nodeId, v);

return;

}

const DSL_Dmatrix &discBeliefs = eqVal->GetDiscBeliefs();

if (discBeliefs.IsEmpty())

{

double mean, stddev, vmin, vmax;

eqVal->GetStats(mean, stddev, vmin, vmax);

printf("%s: mean=%g stddev=%g min=%g max=%g\n",

nodeId, mean, stddev, vmin, vmax);

}

else

{

auto eqDef = node->Def<DSL_equation>();

const DSL_equation::IntervalVector &iv = eqDef->GetDiscIntervals();

printf("%s is discretized.\n", nodeId);

double loBound, hiBound;

eqDef->GetBounds(loBound, hiBound);

double lo = loBound;

for (int i = 0; i < discBeliefs.GetSize(); i++)

{

double hi = iv[i].second;

printf("\tP(%s in %g..%g)=%g\n", nodeId, lo, hi, discBeliefs[i]);

lo = hi;

}

static void UpdateAndShowStats(DSL_network &net)

{

net.UpdateBeliefs();

for (int h = net.GetFirstNode(); h >= 0; h = net.GetNextNode(h))

{

ShowStats(net, h);

}

printf("\n");

}

static void SetUniformIntervals(DSL_network &net, int nodeHandle, int count)

{

auto eq = net.GetNode(nodeHandle)->Def<DSL_equation>();

double lo, hi;

eq->GetBounds(lo, hi);

DSL_equation::IntervalVector iv(count);

for (int i = 0; i < count; i++)

{

iv[i].second = lo + (i + 1) * (hi - lo) / count;

}

eq->SetDiscIntervals(iv);

}