清空筛选条件
清空筛选条件

how to simply result from diff result

1 次查看（过去 30 天）
xueqi
xueqi 2013-6-2
Hi,
I used "diff" to differentiat an symbolic expression (which is a 2*1 matrix in terms of one variable "p1" )and I get the result is
if true
% (993145510909945291290970062799168703243609151945831132541235246491728972506726400000*p1^24)/(11*(66209700727329686086064670853277913549573943463055408836082349766115264833781760*p1^25 + 76000450310455048509674258747439313371109099869460786758580060874282689)) - (3441252636555596989920201187800307357046462757955062829318209447303288193024000000*p1^24*(19108119629907347404438264008256005850407040083437790990093366142500865431029415936*p1^25 - 141284835465018257235063952180851629982268381766690721762239555200372318157))/(11*(66209700727329686086064670853277913549573943463055408836082349766115264833781760*p1^25 + 76000450310455048509674258747439313371109099869460786758580060874282689)^2)
(3441252636555596989920201187800307357046462757955062829318209447303288193024000000*p1^24*(63693732099691158014794213360853352834690133611459303300311220475002884770098053120*p1^25 - 43472257854599900738270425141974962844044977607104383496234591147576231557))/(11*(66209700727329686086064670853277913549573943463055408836082349766115264833781760*p1^25 + 76000450310455048509674258747439313371109099869460786758580060874282689)^2) - (3310485036366484304303233542663895677478697173152770441804117488305763241689088000000*p1^24)/(11*(66209700727329686086064670853277913549573943463055408836082349766115264833781760*p1^25 + 76000450310455048509674258747439313371109099869460786758580060874282689)
end
Anyone can tell me how to simplify this result...I have used "simplify" but the result doesn't look better enough
if true
% (51061483509298234744021093266326713799853337869221735203326270028773557256849240290965339520235810633978267214726144573886032503926667005712580319641600000*p1^24)/(66209700727329686086064670853277913549573943463055408836082349766115264833781760*p1^25 + 76000450310455048509674258747439313371109099869460786758580060874282689)^2
-(36472488679003875759150208868231165720314307528440215941247217470038257246649230534343240731249455251103241160127018820611162429237123481071517696000000000*p1^24)/(66209700727329686086064670853277913549573943463055408836082349766115264833781760*p1^25 + 76000450310455048509674258747439313371109099869460786758580060874282689)^2
end

请先登录，再回答此问题。

回答（1 个）

Roger Stafford
Roger Stafford 2013-6-2
You undoubtedly obtained this kind of baffling result because your original symbolic expression contained numerical values in decimal fraction form. It would be better to use short - preferably single character - symbols for these values before attempting to find the derivative. You can substitute numerical values for these afterward.

类别

在 Help Center 和 File Exchange 中查找有关 Symbolic Math Toolbox 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by