《基于TI DSP的通用算法实现》程序代码

					
					/* Example 2 - 17. Double-Precision Floating-Point Square Root C Listing for sqrt */
					
					/***************************************************************/
					/* SQRDPC.c Syd Poland 6-24-98 _sqrt function in C for 'C67xx */
					/***************************************************************/
					
					double sqrt(double A)
					{
						double ZERO=0.0, HALF=0.5, K15=1.5, AH, X0, X1, X2, X3, Y ;
					
						if (A < ZERO) A = -A ; /* square root of absolute A */
						AH = A * HALF ;
						X0 = _rsqrdp(A) ;
						X1 = X0 * (K15 - (AH*X0)*X0 ) ;
						X2 = X1 * (K15 - (AH*X1)*X1 );
						X3 = X2 * (K15 - (AH*X2)*X2 );
						Y = A * X3 ;
					
						return (Y) ;
					}