Samuel. Raspberry Pi becomes best selling British computer. The Guardian. 2015-02-18 [2016-12-28]. (原始内容存档于2021-03-08). The Mag PiMagazine issue 53, Page
− a Q ( t ) sin ( π t 2 T ) sin ( 2 π f c t ) {\displaystyle s(t)=a_{I}(t)\cos {\left({\frac {{\pi }t}{2T}}\right)}\cos {(2{\pi }f_{c}t)}-a_{Q}(t)\sin
for pi by Leibniz, Gregory, and Nilakantha. Mathematics Magazine. 1990, 63 (5): 291–306. doi:10.2307/2690896. Schepler, H. C. The Chronology of Pi. Mathematics