got rid of the order 4 power series calculations in quaternion_algebra and replaced with order two versions. thats enough and here the forth root seems to be good as threshold.
got rid of the order 4 power series calculations in quaternion_algebra and replaced with order two versions. thats enough and here the forth root seems to be good as threshold.

ethz-asl/Schweizer-Messer,ethz-asl/Schweizer-Messer,ethz-asl/Schweizer-Messer,ethz-asl/Schweizer-Messer