Getting STL container of variables in SymEngine::Expression

[Panagiotis Stavropoulos]

Hello,

I am working in C++. I am trying to get (any) STL container of the variables of a SymEngine::Expression. Lets say for a silly example somewhere in main I have:

SymEngine::Expression ex = SymEngine::Expression("5*x+sqrt(5/4)+1/(y-8)");

I cannot figure out what function to call to get the the variables x and y out of the ex and store them in a container. Any help is appriciated.

[Isuru Fernando]

Hi,

You need to use free_symbols as in https://github.com/symengine/symengine/blob/3c274630c70c242442c051d3db3fe96cf156be2d/symengine/visitor.h#L233

It'll give you a,  std::set<RCP<const Basic>> and you can convert it into any form you like.

Isuru

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[Peter]

Excellent, thank you very much!

On Tuesday, 26 May 2020 16:47:21 UTC-4, Isuru Fernando wrote:

Hi,

You need to use free_symbols as in https://github.com/symengine/symengine/blob/3c274630c70c242442c051d3db3fe96cf156be2d/symengine/visitor.h#L233

It'll give you a,  std::set<RCP<const Basic>> and you can convert it into any form you like.

Isuru

On Tue, May 26, 2020 at 3:37 PM Panagiotis Stavropoulos <peter...@gmail.com> wrote:

Hello,

I am working in C++. I am trying to get (any) STL container of the variables of a SymEngine::Expression. Lets say for a silly example somewhere in main I have:

SymEngine::Expression ex = SymEngine::Expression("5*x+sqrt(5/4)+1/(y-8)");

I cannot figure out what function to call to get the the variables x and y out of the ex and store them in a container. Any help is appriciated.

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