1 files changed, 64 insertions, 0 deletions
diff --git a/Project/TestCode/dft.c b/Project/TestCode/dft.c
new file mode 100644
index 0000000..e82cb3e
--- /dev/null
+++ b/Project/TestCode/dft.c
@@ -0,0 +1,64 @@
+#include <math.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#define E_PI 3.1415926535897932384626433832795028841971693993751058209749445923078164062
+#define N_DEF 8
+
+typedef struct {
+    float r;
+    float i;
+} Complex;
+
+float x[] = {0, 0, 2, 3, 4, 0, 0, 0};
+
+void dft(int N, Complex *X) {
+    int i, n, k;
+    Complex *x = malloc(N * sizeof(X[0]));
+	for(i = 0; i < N; ++i) {
+		x[i] = X[i];
+	}
+    for(k = 0; k < N; ++k) {
+        X[k].r = 0.f;
+        X[k].i = 0.f;
+        for(n = 0; n < N; ++n) {
+            X[k].r += x[n].r * cos(2 * E_PI * k * n / N);
+            X[k].i -= x[n].r * sin(2 * E_PI * k * n / N);
+        }
+    }
+    free(x);
+}
+
+void idft(int N, Complex *X) {
+    int i, n, k;
+	Complex *x = malloc(N * sizeof(X[0]));
+	for(i = 0; i < N; ++i) {
+		x[i] = X[i];
+	}
+    for(n = 0; n < N; ++n) {
+        X[n].i = 0.f;
+		X[n].r = 0.f;
+        for(k = 0; k < N; ++k) {
+            X[n].r += x[k].r * cos(2 * E_PI * k * n / N) - x[k].i * sin(2 * E_PI * k * n / N);
+        }
+        X[n].r /= N;
+    }
+    free(x);
+}
+
+int main() {
+    int k;
+    Complex X_C[8];
+    for(k = 0; k < N_DEF; ++k) {
+        X_C[k].r = x[k];
+        X_C[k].i = 0;
+    }
+    dft(N_DEF, X_C);
+    for(k = 0; k < N_DEF; ++k) {
+        printf("x[%d] = %.2f, X[%d] = %.2f + %.2fi\n", k, x[k], k, X_C[k].r, X_C[k].i);
+    }
+    idft(N_DEF, X_C);
+    for(k = 0; k < N_DEF; ++k) {
+        printf("x[%d] = %.2f, X[%d] = %.2f + %.2fi\n", k, x[k], k, X_C[k].r, X_C[k].i);
+    }
+}