[mathjiang]

没有问题：
>>t = linspace(0.pi/25,100);
>>s = (26530395678209226457619503764425*cos(50*t +1172225986512927/1125899906842624))/10384593717069655257060992658440192 - (3921262612261847544424056738285*cos(50*t - 2867198305555969/2251799813685248))/664613997892457936451903530140172288 - (9691159285721898847827030356517*cos(50*t + 3489485939873631/2251799813685248))/20769187434139310514121985316880384;
plot(t,s)

不知道怎么贴图片。