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

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Yugal Gupta 2021-8-8

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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 ?

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Yugal Gupta 2021-8-9

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

combine(ysincoss,'sincos')

Walter Roberson 2021-8-9

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

combine(y, 'sincos')

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Gargi Patil 2021-8-12

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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 =