added a new air density (rho) estimator dialog box, hooked it into the Tools menu, and updated src.pro to add compilation dependencies for it

src/MainWindow.cpp

@@ -50,6 +50,7 @@
 #include "RideCalendar.h"
 #include "DatePickerDialog.h"
 #include "ToolsDialog.h"
+#include "ToolsRhoEstimator.h"
 #include "MetricAggregator.h"
 #include "SplitActivityWizard.h"
 #include "BatchExportDialog.h"
@@ -610,6 +611,7 @@ MainWindow::MainWindow(const QDir &home) :
     QMenu *optionsMenu = menuBar()->addMenu(tr("&Tools"));
     optionsMenu->addAction(tr("&Options..."), this, SLOT(showOptions()), tr("Ctrl+O"));
     optionsMenu->addAction(tr("Critical Power Calculator..."), this, SLOT(showTools()));
+    optionsMenu->addAction(tr("Air Density (Rho) Estimator..."), this, SLOT(showRhoEstimator()));
 
     optionsMenu->addSeparator();
     optionsMenu->addAction(tr("Workout Wizard"), this, SLOT(showWorkoutWizard()));
@@ -1075,6 +1077,12 @@ void MainWindow::showTools()
    td->show();
 }
 
+void MainWindow::showRhoEstimator()
+{
+   ToolsRhoEstimator *tre = new ToolsRhoEstimator();
+   tre->show();
+}
+
 void MainWindow::showWorkoutWizard()
 {
    WorkoutWizard *ww = new WorkoutWizard(this);

src/MainWindow.h

@@ -245,6 +245,7 @@ class MainWindow : public QMainWindow
         bool saveRideExitDialog();              // save dirty rides on exit dialog
         void showOptions();
         void showTools();
+        void showRhoEstimator();
         void toggleSidebar();
         void showSidebar(bool want);
         void showToolbar(bool want);

src/ToolsRhoEstimator.cpp

@@ -0,0 +1,288 @@
+/*
+ * Copyright (c) Steven Gribble (gribble [at] gmail [dot] com)
+ * http://www.gribble.org/
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301 USA.
+ */
+
+#include "ToolsRhoEstimator.h"
+#include "Settings.h"
+#include "Units.h"
+#include <QtGui>
+#include <sstream>
+#include <cmath>
+
+typedef QDoubleSpinBox* QDoubleSpinBoxPtr;
+
+ToolsRhoEstimator::ToolsRhoEstimator(QWidget *parent) : QDialog(parent) {
+  // Does the user prefer metric or imperial?  Set the initial radio
+  // button and field settings to their GoldenCheetah preference.
+  QVariant unit = appsettings->value(NULL, GC_UNIT);
+  useMetricUnits = (unit.toString() == "Metric");
+
+  // Set the main window title.
+  setWindowTitle(tr("Air Density (Rho) Estimator"));
+  setAttribute(Qt::WA_DeleteOnClose);
+
+  // Create the main layout box.
+  QVBoxLayout *mainVBox = new QVBoxLayout(this);
+
+  // Set up the instructions field.
+  mainVBox->addWidget(new QLabel(
+       tr("Enter measured values for the following:")));
+  mainVBox->addSpacing(5);
+
+  // "metric vs. imperial" radio buttons.  (Makes it easier than
+  // forcing them to change their preference in the preferences menu.)
+  QHBoxLayout *rads = new QHBoxLayout;
+  metBut = new QRadioButton(tr("Metric"));
+  metBut->setChecked(useMetricUnits);
+  rads->addWidget(metBut);
+  impBut = new QRadioButton(tr("Imperial"));
+  impBut->setChecked(!useMetricUnits);
+  // note that we only need to connect one of the radio button
+  // signals, since changing one also changes the other.
+  connect(impBut, SIGNAL(toggled(bool)),
+          this, SLOT(on_radio_toggled(bool)));
+  rads->addWidget(impBut);
+  mainVBox->addLayout(rads);
+
+  // The temperature box.
+  QHBoxLayout *thl = new QHBoxLayout;
+  tempSpinBox = new QDoubleSpinBox(this);
+  tempSpinBox->setDecimals(2);
+  tempSpinBox->setRange(-200, 200);
+  if (useMetricUnits) {
+    tempLabel = new QLabel("Temperature (C):");
+    thl->addWidget(tempLabel);
+    tempSpinBox->setValue(15);
+  } else {
+    tempLabel = new QLabel("Temperature (F):");
+    thl->addWidget(tempLabel);
+    tempSpinBox->setValue(59);
+  }
+  tempSpinBox->setWrapping(false);
+  tempSpinBox->setAlignment(Qt::AlignRight);
+  connect(tempSpinBox, SIGNAL(valueChanged(double)),
+          this, SLOT(on_valueChanged(double)));
+  thl->addWidget(tempSpinBox);
+  mainVBox->addLayout(thl);
+
+  // The air pressure box.
+  QHBoxLayout *phl = new QHBoxLayout;
+  pressSpinBox = new QDoubleSpinBox(this);
+  pressSpinBox->setDecimals(2);
+  pressSpinBox->setRange(0, 2000);
+  if (useMetricUnits) {
+    pressLabel = new QLabel("Air Pressure (hPa):");
+    phl->addWidget(pressLabel);
+    pressSpinBox->setValue(1018);
+  } else {
+    pressLabel = new QLabel("Air Pressure (inHg):");
+    phl->addWidget(pressLabel);
+    pressSpinBox->setValue(30.06);
+  }
+  pressSpinBox->setWrapping(false);
+  pressSpinBox->setAlignment(Qt::AlignRight);
+  connect(pressSpinBox, SIGNAL(valueChanged(double)),
+          this, SLOT(on_valueChanged(double)));
+  phl->addWidget(pressSpinBox);
+  mainVBox->addLayout(phl);
+
+  // The dewpoint box.
+  QHBoxLayout *dhl = new QHBoxLayout;
+  dewpSpinBox = new QDoubleSpinBox(this);
+  dewpSpinBox->setDecimals(2);
+  dewpSpinBox->setRange(-200, 200);
+  if (useMetricUnits) {
+    dewpLabel = new QLabel("Dewpoint (C):");
+    dhl->addWidget(dewpLabel);
+    dewpSpinBox->setValue(7.5);
+  } else {
+    dewpLabel = new QLabel("Dewpoint (F):");
+    dhl->addWidget(dewpLabel);
+    dewpSpinBox->setValue(45.5);
+  }
+  dewpSpinBox->setWrapping(false);
+  dewpSpinBox->setAlignment(Qt::AlignRight);
+  connect(dewpSpinBox, SIGNAL(valueChanged(double)),
+          this, SLOT(on_valueChanged(double)));
+  dhl->addWidget(dewpSpinBox);
+  mainVBox->addLayout(dhl);
+
+  // Label for the computed air density.
+  mainVBox->addSpacing(15);
+  mainVBox->addWidget(new QLabel(
+        tr("Estimated air density (rho):")));
+
+  // Estimated Rho (metric units).
+  QHBoxLayout *rhoMetHBox = new QHBoxLayout;
+  txtRhoMet = new QLineEdit(this);
+  txtRhoMet->setAlignment(Qt::AlignRight);
+  txtRhoMet->setReadOnly(true);
+  rhoMetHBox->addWidget(txtRhoMet);
+  rhoMetHBox->addWidget(new QLabel(tr("(kg/m^3)")));
+  mainVBox->addLayout(rhoMetHBox);
+
+  // Estimated Rho (imperial units).
+  QHBoxLayout *rhoImpHBox = new QHBoxLayout;
+  txtRhoImp = new QLineEdit(this);
+  txtRhoImp->setAlignment(Qt::AlignRight);
+  txtRhoImp->setReadOnly(true);
+  rhoImpHBox->addWidget(txtRhoImp);
+  rhoImpHBox->addWidget(new QLabel(tr("(lb/ft^3)")));
+  mainVBox->addLayout(rhoImpHBox);
+
+  // "Done" button.
+  mainVBox->addSpacing(15);
+  QHBoxLayout *buttonHBox = new QHBoxLayout;
+  btnOK = new QPushButton(this);
+  btnOK->setText(tr("Done"));
+  buttonHBox->addWidget(btnOK);
+  mainVBox->addLayout(buttonHBox);
+  connect(btnOK, SIGNAL(clicked()), this, SLOT(on_btnOK_clicked()));
+
+  // Force the initial "rho" calculation when the dialog box comes up
+  // initially.
+  this->on_valueChanged(0.0);
+}
+
+void ToolsRhoEstimator::on_radio_toggled(bool checked) {
+  checked = true;  // hack to avoid the "unused parameter" g++ warning
+
+  if (impBut->isChecked()) {
+    // we just changed from metric --> imperial, so relabel and do the
+    // field conversions for the user.
+    tempSpinBox->setValue(celsius_to_fahrenheit(tempSpinBox->value()));
+    tempLabel->setText("Temperature (F):");
+    pressSpinBox->setValue(
+        hectopascals_to_inchesmercury(pressSpinBox->value()));
+    pressLabel->setText("Air Pressure (inHg):");
+    dewpSpinBox->setValue(celsius_to_fahrenheit(dewpSpinBox->value()));
+    dewpLabel->setText("Dewpoint (F):");
+  } else {
+    // we just changed from imperial --> metric, so relabel and do the
+    // field conversions for the user.
+    tempSpinBox->setValue(fahrenheit_to_celsius(tempSpinBox->value()));
+    tempLabel->setText("Temperature (C):");
+    pressSpinBox->setValue(
+        inchesmercury_to_hectopascals(pressSpinBox->value()));
+    pressLabel->setText("Air Pressure (hPa):");
+    dewpSpinBox->setValue(fahrenheit_to_celsius(dewpSpinBox->value()));
+    dewpLabel->setText("Dewpoint (C):");
+  }
+
+  // Relay the "something has changed" signal to
+  // on_valueChanged(double).
+  this->on_valueChanged(0.0);
+}
+
+void ToolsRhoEstimator::on_btnOK_clicked() {
+  // all done!
+  accept();
+}
+
+void ToolsRhoEstimator::on_valueChanged(double newval) {
+  newval++;  // hack to avoid the "unused parameter" g++ warning.
+
+  // scrape the field values, convert to metric if needed.
+  double temp = tempSpinBox->value();
+  double press = pressSpinBox->value();
+  double dewp = dewpSpinBox->value();
+  if (impBut->isChecked()) {
+    // yup, convert to metric.
+    temp = fahrenheit_to_celsius(temp);
+    press = inchesmercury_to_hectopascals(press);
+    dewp = fahrenheit_to_celsius(dewp);
+  }
+
+  // calculate rho, in (kg/m^3)
+  double rho_met = calculate_rho(temp, press, dewp);
+  // calculate rho in imperial units.
+  double rho_imp = rho_met_to_imp(rho_met);
+
+  // display the calculated Rho's.
+  std::stringstream ss_met, ss_imp;
+  ss_met.precision(6);
+  ss_met << rho_met;
+  txtRhoMet->setText(tr(ss_met.str().c_str()));
+  ss_imp.precision(6);
+  ss_imp << rho_imp;
+  txtRhoImp->setText(tr(ss_imp.str().c_str()));
+}
+
+double ToolsRhoEstimator::fahrenheit_to_celsius(double f) {
+  return (f - 32.0) * (5.0/9.0);
+}
+
+double ToolsRhoEstimator::celsius_to_fahrenheit(double c) {
+    return (c * 9.0 / 5.0) + 32.0;
+}
+
+double ToolsRhoEstimator::hectopascals_to_inchesmercury(double hpa) {
+  return (hpa / 1000.0) * 29.53;
+}
+
+double ToolsRhoEstimator::inchesmercury_to_hectopascals(double inhg) {
+  return (inhg * 1000.0) / 29.53;
+}
+
+double ToolsRhoEstimator::rho_met_to_imp(double rho) {
+  return rho * ((0.30480061 * 0.30480061 * 0.30480061) / 0.45359237);
+}
+
+double ToolsRhoEstimator::calculate_rho(double temp,
+                                        double press,
+                                        double dewp) {
+  // Step 1: calculate the saturation water pressure at the dew point,
+  // i.e., the vapor pressure in the air.  Use Herman Wobus' equation.
+  double c0 = 0.99999683;
+  double c1 = -0.90826951E-02;
+  double c2 = 0.78736169E-04;
+  double c3 = -0.61117958E-06;
+  double c4 = 0.43884187E-08;
+  double c5 = -0.29883885E-10;
+  double c6 = 0.21874425E-12;
+  double c7 = -0.17892321E-14;
+  double c8 = 0.11112018E-16;
+  double c9 = -0.30994571E-19;
+  double p = c0 +
+    dewp*(c1 +
+          dewp*(c2 +
+                dewp*(c3 +
+                      dewp*(c4 +
+                            dewp*(c5 +
+                                  dewp*(c6 +
+                                        dewp*(c7 +
+                                              dewp*(c8 +
+                                                    dewp*(c9)))))))));
+  double psat_mbar = 6.1078 / std::pow(p, 8);
+
+  // Step 2: calculate the vapor pressure.
+  double pv_pascals = psat_mbar * 100.0;
+
+  // Step 3: calculate the pressure of dry air, given the vapor
+  // pressure and actual pressure.
+  double pd_pascals = (press*100) - pv_pascals;
+
+  // Step 4: calculate the air density, using the equation for
+  // the density of a mixture of dry air and water vapor.
+  double density =
+    (pd_pascals / (287.0531 * (temp + 273.15))) +
+    (pv_pascals / (461.4964 * (temp + 273.15)));
+
+  return density;
+}

src/ToolsRhoEstimator.h

@@ -0,0 +1,60 @@
+/*
+ * Copyright (c) 2012 Steven Gribble (gribble [at] gmail [dot] com)
+ * http://www.gribble.org/
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301 USA.
+ */
+
+#include "GoldenCheetah.h"
+
+#include <QDateTime>
+#include <QtGui>
+
+// This class implements a dialog box containing a tool for
+// helping the user estimate rho, the air density, given
+// temperature, pressure, and dew point as inputs.
+class ToolsRhoEstimator : public QDialog {
+        Q_OBJECT
+        G_OBJECT
+
+    public:
+        ToolsRhoEstimator(QWidget *parent = 0);
+
+    private:
+        bool useMetricUnits;
+        QRadioButton *metBut;
+        QRadioButton *impBut;
+        QPushButton *btnOK;
+        QLineEdit *txtRhoImp;
+        QLineEdit *txtRhoMet;
+        QLabel *tempLabel;
+        QLabel *pressLabel;
+        QLabel *dewpLabel;
+        QDoubleSpinBox *tempSpinBox;
+        QDoubleSpinBox *pressSpinBox;
+        QDoubleSpinBox *dewpSpinBox;
+        double fahrenheit_to_celsius(double f);
+        double celsius_to_fahrenheit(double c);
+        double hectopascals_to_inchesmercury(double hpa);
+        double inchesmercury_to_hectopascals(double inhg);
+        double rho_met_to_imp(double rho);
+        double calculate_rho(double temp, double press, double dewp);
+
+    private slots:
+        void on_radio_toggled(bool checked);
+        void on_btnOK_clicked();
+        void on_valueChanged(double newval);
+};

src/src.pro

@@ -328,6 +328,7 @@ HEADERS += \
         TxtRideFile.h \
         TimeUtils.h \
         ToolsDialog.h \
+        ToolsRhoEstimator.h \
         TrainTool.h \
         TreeMapWindow.h \
         TreeMapPlot.h \
@@ -506,6 +507,7 @@ SOURCES += \
         TimeInZone.cpp \
         TimeUtils.cpp \
         ToolsDialog.cpp \
+        ToolsRhoEstimator.cpp \
         TrainTool.cpp \
         TreeMapWindow.cpp \
         TreeMapPlot.cpp \