efficient way to compute xe^(-x^2/a) and x / (1 + x^2/a) for IPP

Hi, 

          I am wondering if IPP 8.0 has any way to efficiently implement the xe^{(-x^2/a)}, where a is a positive float number (ipp32f), where x is an array (potential large array) of data type ipp32f. I have used IPP 8.0 to element-wise product of x and e^{(-x^2/a)}, where i have used additional function call to compute the power component of the exponent (i.e., -x^2/a ). Due to multiple function calls, the evaluation of the above function becomes the bottleneck. Similar arguments applies to the x / (1 + x^2/a) as well. Is there any function calls respectively that I can directly compute the above two formula? 

Best Regards

Edwin