试用软件

Extracting coefficients of 'sinwt', 'coswt', sin2wt etc from a symbiolic expression.

7 次查看（过去 30 天）

显示更早的评论

Yugal Gupta 2021-8-8

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/894797-extracting-coefficients-of-sinwt-coswt-sin2wt-etc-from-a-symbiolic-expression

编辑： Walter Roberson 2021-8-12

Hello,

I am having a mathmatical symbolic expression and want to extract the coefficient of 'sinwt', 'coswt', 'sin2wt' and so on.

For e.g. the expression is,

where,

,

and

are symbolic variables. Now, is there anyway to get the coefficient of 'sinwt', 'coswt', 'cos3wt' etc. from this expression ? or in other words, is it possible to get the following desired output ?

5 个评论
显示 3更早的评论隐藏 3更早的评论

Yugal Gupta 2021-8-9

在 MATLAB Online 中打开

In the end, I added the following code and it gives me the desired output.

combine(ysincoss,'sincos')

Walter Roberson 2021-8-9

在 MATLAB Online 中打开

Ah... you can get there in a single step with

combine(y, 'sincos')

请先登录，再进行评论。

请先登录，再回答此问题。

回答（1 个）

Gargi Patil 2021-8-12

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/894797-extracting-coefficients-of-sinwt-coswt-sin2wt-etc-from-a-symbiolic-expression#answer_765677

在 MATLAB Online 中打开

Hi,

My understanding is that you would like to extract the coefficients of a symbolic trigonometric expression. The function "coeffs" can be used to return coefficients of an expression with respect to a specified term as follows:

syms a b c x

expr = a*sin(x)*b*sin(2*x) + c*sin(x);

[csin, tsin] = coeffs(expr, [sin(x), sin(2*x)])

csin =

tsin =

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Walter Roberson 2021-8-12

编辑：Walter Roberson 2021-8-12

It turned out that they wanted the express rewritten in terms of cos(), and were not looking for coefficients such as you get with coeffs(); see https://www.mathworks.com/matlabcentral/answers/894797-extracting-coefficients-of-sinwt-coswt-sin2wt-etc-from-a-symbiolic-expression#comment_1679322

请先登录，再进行评论。

请先登录，再回答此问题。

类别

Mathematics and Optimization Symbolic Math Toolbox Mathematics Formula Manipulation and Simplification

在 Help Center 和 File Exchange 中查找有关 Formula Manipulation and Simplification 的更多信息

标签

Community Treasure Hunt

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

Translated by

试用软件