Improved documentation for issue ARM-software#156

Author: christophe0606

Source/FastMathFunctions/arm_atan2_f16.c

@@ -113,7 +113,7 @@ __STATIC_FORCEINLINE float16_t arm_atan_f16(float16_t x)
  
   @par         Compute the Arc tangent of y/x:
                    The sign of y and x are used to determine the right quadrant
-                   and compute the right angle.
+                   and compute the right angle. Returned value is between -Pi and Pi.
 
 */
 arm_status arm_atan2_f16(float16_t y,float16_t x,float16_t *result)

Source/FastMathFunctions/arm_atan2_f32.c

@@ -125,7 +125,7 @@ __STATIC_FORCEINLINE float32_t arm_atan_f32(float32_t x)
  
   @par         Compute the Arc tangent of y/x:
                    The sign of y and x are used to determine the right quadrant
-                   and compute the right angle.
+                   and compute the right angle. Returned value is between -Pi and Pi.
 */
 
 

Source/FastMathFunctions/arm_atan2_q15.c

@@ -178,7 +178,7 @@ __STATIC_FORCEINLINE q15_t arm_atan_q15(q15_t y,q15_t x)
  
   @par         Compute the Arc tangent of y/x:
                    The sign of y and x are used to determine the right quadrant
-                   and compute the right angle.
+                   and compute the right angle. Returned value is between -Pi and Pi.
 */
 
 

Source/FastMathFunctions/arm_atan2_q31.c

@@ -178,7 +178,7 @@ __STATIC_FORCEINLINE q31_t arm_atan_q31(q31_t y,q31_t x)
  
   @par         Compute the Arc tangent of y/x:
                    The sign of y and x are used to determine the right quadrant
-                   and compute the right angle.
+                   and compute the right angle. Returned value is between -Pi and Pi.
 */