I know this is not a timely response.... but what the hell.... right ?
You are "Assuming" that
@Simonka has ass jiggle, but me thinks that's probably much less than one may guess, if you look at her photo's you see that she is rather firm and petite... granted no "First Hand" knowledge
, but that's just my guess.... as for the sine/co-sine.... you would need her to provide data points for your calculations (by slide rule only plz) as to the force of the jiggle, Finite Element Analysis software could be used, but you would need sensors to determine the exact force... tri-axial data would be required for the X-Y-Z axis to determine precise force... I read a study where researchers were trying to determine the force shrimp create when moving their "legs".... and if it creates cavitation. but I digress..... I hope to read the paper you author on this topic.
As for your SB.... she wants money without the honey... when she says she on her period... just say.... SOooooo that you are cool with that. Use a towel.... call her bluff... I know my thinking about SB is a little slanted.... (I believe SB should also include sex) but there are loads of women/girls out there that do not have the same opinion as me on this topic. If this is the case then you need to be straight up with here... You pay her xxxxJPY/month or meeting and you expect (dinner, movie, talk, sex) If she says no to the sex, then you drop your allowance proportionately to what her company is worth to you. Of course she is going to overvalue herself.... I'm not saying all women do this, but from your description... she seems to believe that she is soooo amazing that you are lucky to pay her what she is asking... if she can get it then good on her, but don't let her dictate the terms...they should be negotiated to mutual agreement... SB is a business arrangement between 2 people. the other stuff that happens is between 2 consenting adults... If she says you are "cheap" because you want to negotiate the amount... tell her that she keeps changing the amount back to original, but original amount was based on sex. and since that has not happened (i'm assuming this) then the rate needs to be re-negotiated, otherwise you can always find a new SB.... That is unless you have told her how pretty she is and amazing she is and how lucky you are to spend time with her... blah blah bah.... then my friend you are stuck... time to move on to another SB IMO...
OK... so I know that my words may seem a bit harsh, but how long you work for the cash you are spending ? it has to equal some hours yes ? so have you reached your equilibrium on cash and satisfaction with this "almost SB" ? ? ? If not, then it's not worth the investment you have made... time to cash out and find a new SB to invest in... again just my opinion. and quite late at that....