不韋 呂 / Mbed 2 deprecated DSP_Seminar_FunctionGenerator

CQエレクトロニクス・セミナで使用するファンクション・ジェネレータの プログラム

Dependencies:   Array_Matrix mbed SerialTxRxIntr MyTicker7

Diff: FastSin.hpp

Revision:
0:8c8bc21159d9
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/FastSin.hpp	Fri Feb 25 02:36:55 2022 +0000
@@ -0,0 +1,26 @@
+//-----------------------------------------------------------
+//  FastSin() 関数
+//      sin(πx/2) の値の計算
+//
+//  2020/06/01, Copyright (c) 2020 MIKAMI, Naoki
+//-----------------------------------------------------------
+
+#ifndef FASTSIN_POLYNOMIAL_HPP
+#define FASTSIN_POLYNOMIAL_HPP
+
+namespace Mikami
+{
+    // 引数の範囲： -2 <= x <= 2
+    inline float FastSin(float x)
+    {
+        static const float A1 =  1.570320019210f;
+        static const float A3 = -0.642113166941f;
+        static const float A5 =  0.071860854119f;
+
+        if (x >  1.0f) x =  2.0f - x;
+        if (x < -1.0f) x = -2.0f - x;
+        float x2 = x*x;
+        return ((A5*x2 + A3)*x2 + A1)*x;
+    }
+}
+#endif  // FASTSIN_POLYNOMIAL_HPP