We discussedyour requestinternally, itmay notmake sense to change behavior of ippModf or add new function that returns only fractional part into IPP VM without visible perfrormance gain. But considering it is normal for MKL routine to accept the null pointer as input, we think it is make sense to add new routine for fractional part into MKL, so esclate the feature request to MKL team.MKL team have agreed to add such functionality in MKL. Could you please let me know if a new MKL routine can help you?
MKL VML: http://software.intel.com/sites/products/documentation/hpc/mkl/vml/vmldata.htm
I heard from our IPP team. two new functions ippsFrac_32f and ippsFrac_64f have been added to ippVM to support the feature you mentioned here. The release will be targeted to ready at the Sept.(we shall have a notification here when new version release) . You are welcomed to try by that time.