清空筛选条件
清空筛选条件

How to get every term of a sum thats not multiplied by a convergent exponential function?

2 次查看（过去 30 天）
Hansi K
Hansi K 2023-12-5
评论： Walter Roberson 2023-12-6
Ran in:
Hey, I need every term of a sum thats not multiplied by a convergent exponential function. In my case:
syms t
G = exp(-t)*cos(t) + 3*exp(-2*t)*sin(2*t) + 1/2*cos(4*t) + 1/5
G = 
What I need is stored in a variable. Is there any MATLAB function that fits my purpose?

请先登录，再回答此问题。

采纳的回答

Walter Roberson
Walter Roberson 2023-12-5
Ran in:
Not exactly what you asked, but
syms t
G = exp(-t)*cos(t) + 3*exp(-2*t)*sin(2*t) + 1/2*cos(4*t) + 1/5
G = 
mapSymType(G, 'exp', @(varargin) 0)
ans = 
The reason it is not exactly what you asked is that you specified "not multipled by a convergent exponential function", implying that you would want a term with exp(5*t) [for example] to be retained as that is not convergent. So the parameter to the exp() needs to be examined to determine whether the exp() would be convergent or not.
  1 个评论
Walter Roberson
Walter Roberson 2023-12-6
Ran in:
syms t
G = exp(-t)*cos(t) + 3*exp(-2*t)*sin(2*t) + 1/2*cos(4*t) + 1/5 + 5*exp(7*t)
G = 
H = mapSymType(G, 'exp', @(EXPR) piecewise(LimitIsInf(children(EXPR,1)), EXPR, sym(0)))
H = 
function tf = LimitIsInf(EXPR)
var = symvar(EXPR,1);
if ~isempty(var)
tf = isAlways(limit(EXPR,var,inf)==inf, 'unknown', "true");
else
tf = isAlways(~isfinite(EXPR), 'unknown', "true");
end
tf = tf == symtrue;
end

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Number Theory 的更多信息

标签

产品


版本

R2023a

Community Treasure Hunt

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

Start Hunting!

Translated by