Added dft again

1 files changed, 46 insertions, 0 deletions

diff --git a/Project/TestCode/dft.c b/Project/TestCode/dft.c
new file mode 100644
index 0000000..9ffcfbe
--- /dev/null
+++ b/Project/TestCode/dft.c
@@ -0,0 +1,46 @@
+#include <math.h>
+#include <stdio.h>
+
+#define E_PI 3.1415926535897932384626433832795028841971693993751058209749445923078164062
+#define N 8
+
+typedef struct {
+    float r;
+    float i;
+} Complex;
+
+float x[] = {0, 0, 2, 3, 4, 0, 0, 0};
+Complex X[N];
+float x_out[N];
+
+void dft() {
+    int n, k;
+    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] * cos(2 * E_PI * k * n / N);
+            X[k].i -= x[n] * sin(2 * E_PI * k * n / N);
+        }
+    }
+}
+
+void idft() {
+    int n, k;
+    for(n = 0; n < N; ++n) {
+        x_out[n] = 0.f;
+        for(k = 0; k < N; ++k) {
+            x_out[n] += X[k].r * cos(2 * E_PI * k * n / N) - X[k].i * sin(2 * E_PI * k * n / N);
+        }
+        x_out[n] /= N;
+    }
+}
+
+int main() {
+    int k;
+    dft();
+    idft();
+    for(k = 0; k < N; ++k) {
+        printf("x[%d] = %.2f, X[%d] = %.2f + %.2fi, x_out[%d] = %.2f\n", k, x[k], k, X[k].r, X[k].i, k, x_out[k]);
+    }
+}
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