From 6eea0acaeabaa9eb6b1cadbfeb99a4f01ca64a9b Mon Sep 17 00:00:00 2001
From: Youwen Wu <youwenw@gmail.com>
Date: Tue, 21 Jan 2025 21:01:07 -0800
Subject: [PATCH] auto-update(nvim): 2025-01-21 21:01:07

---
 meson.build                         |   1 +
 src/chapter_2/program_1/main.cpp    | 117 ++++++++++++++++++++++++++++
 src/chapter_2/program_1/tunnel1.dat |  17 ++++
 src/chapter_2/program_1/tunnel2.dat |  17 ++++
 4 files changed, 152 insertions(+)
 create mode 100644 src/chapter_2/program_1/main.cpp
 create mode 100644 src/chapter_2/program_1/tunnel1.dat
 create mode 100644 src/chapter_2/program_1/tunnel2.dat

diff --git a/meson.build b/meson.build
index ea4d3e1..6fcaab6 100644
--- a/meson.build
+++ b/meson.build
@@ -18,3 +18,4 @@ c_2_lab_1_arg = executable(
 
 c_2_lab_2 = executable('c_2_lab_2', 'src/chapter_2/lab_2/main.cpp', install: true)
 c_2_lab_3 = executable('c_2_lab_3', 'src/chapter_2/lab_3/main.cpp', install: true)
+c_2_program_1 = executable('c_2_program_1', 'src/chapter_2/program_1/main.cpp', install: true)
diff --git a/src/chapter_2/program_1/main.cpp b/src/chapter_2/program_1/main.cpp
new file mode 100644
index 0000000..2686061
--- /dev/null
+++ b/src/chapter_2/program_1/main.cpp
@@ -0,0 +1,117 @@
+using namespace std;
+#include <fstream>
+#include <iostream>
+#include <sstream>
+#include <string>
+#include <vector>
+
+void readData(const string &, vector<double> &, vector<double> &);
+double interpolation(double, vector<double> &, vector<double> &);
+bool isOrdered(const vector<double> &);
+void reorder(vector<double> &, vector<double> &);
+
+void readData(const string &filename, vector<double> &angles,
+              vector<double> &coefficients) {
+  double angle;
+  double coefficient;
+  string line;
+  stringstream line_s;
+  fstream csv = fstream(filename);
+
+  if (!csv.is_open()) {
+    cout << "Error opening " << filename << endl;
+    exit(1);
+  }
+
+  while (getline(csv, line)) {
+    line_s = stringstream(line);
+    line_s >> angle;
+    line_s >> coefficient;
+    angles.push_back(angle);
+    coefficients.push_back(coefficient);
+  }
+}
+
+bool isOrdered(const vector<double> &angles) {
+  if (angles.size() <= 1)
+    return true;
+  for (unsigned int i = 1; i < angles.size(); i++) {
+    if (angles.at(i) < angles.at(i - 1)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+void reorder(vector<double> &angles, vector<double> &coefficients) {
+  unsigned int i;
+  unsigned int j;
+  double temp;
+  if (angles.size() <= 1)
+    return;
+  for (i = 0; i < angles.size(); i++) {
+    for (j = i + 1; j < angles.size(); j++) {
+      if (angles.at(j) < angles.at(i)) {
+        temp = angles.at(j);
+        angles.at(j) = angles.at(i);
+        angles.at(i) = temp;
+        temp = coefficients.at(j);
+        coefficients.at(j) = coefficients.at(i);
+        coefficients.at(i) = temp;
+      }
+    }
+  }
+}
+
+double interpolation(const double target_angle, vector<double> &angles,
+                     vector<double> &coefficients) {
+  unsigned int upper = 0;
+  unsigned int lower = 0;
+
+  if (!isOrdered(angles)) {
+    reorder(angles, coefficients);
+  }
+
+  if (angles.back() < target_angle) {
+    lower = angles.size() - 2;
+    upper = angles.size() - 1;
+  } else if (angles.at(0) > target_angle) {
+    lower = 0;
+    upper = 1;
+  } else {
+    unsigned int i = 0;
+    while (i < angles.size() && angles.at(i) <= target_angle) {
+      if (angles.at(i) == target_angle) {
+        return coefficients.at(i);
+      }
+      lower = i;
+      i++;
+    }
+    upper = i;
+  }
+
+  return coefficients.at(lower) +
+         (((target_angle - angles.at(lower)) /
+           (angles.at(upper) - angles.at(lower))) *
+          (coefficients.at(upper) - coefficients.at(lower)));
+}
+
+int main(int argc, char *argv[]) {
+  vector<double> angles;
+  vector<double> coefficients;
+  double target_angle;
+  bool shouldRepeat = true;
+  string userResponse;
+  string filename = argv[1];
+
+  readData(filename, angles, coefficients);
+
+  while (shouldRepeat) {
+    cout << "Enter an angle:" << endl;
+    cin >> target_angle;
+    cout << interpolation(target_angle, angles, coefficients) << endl;
+    cout << "Want to enter another angle? (y/n)" << endl;
+    cin >> userResponse;
+    shouldRepeat = userResponse == "Yes";
+  }
+}
diff --git a/src/chapter_2/program_1/tunnel1.dat b/src/chapter_2/program_1/tunnel1.dat
new file mode 100644
index 0000000..b08f159
--- /dev/null
+++ b/src/chapter_2/program_1/tunnel1.dat
@@ -0,0 +1,17 @@
+-4.0 -0.182
+-2.0 -0.056
+0.0 0.097
+2.0 0.238
+4.0 0.421
+6.0 0.479
+8.0 0.654
+10.0 0.792
+12.0 0.924
+14.0 1.035
+15.0 1.076
+16.0 1.103
+17.0 1.120
+18.0 1.121
+19.0 1.121
+20.0 1.099
+21.0 1.059
diff --git a/src/chapter_2/program_1/tunnel2.dat b/src/chapter_2/program_1/tunnel2.dat
new file mode 100644
index 0000000..6d37066
--- /dev/null
+++ b/src/chapter_2/program_1/tunnel2.dat
@@ -0,0 +1,17 @@
+-2 -0.056
+21 1.059
+4 0.421
+2 0.238
+20 1.099
+12 0.924
+6 0.479
+-4 -0.182
+8 0.654
+10 0.792
+0 0.097
+14 1.035
+16 1.103
+18 1.121
+15 1.076
+19 1.121
+17 1.120
\ No newline at end of file