Evaluate expression for a variable(s) set to a number

#1 Posted: 4/10/2014 4:26:17 PM

127 likes in 494 posts.

Group: Moderator

Hi All,

So I am using Smath Studio for personal projects (I am converting from Mathematica that I no longer have access to).

Here is a very simple task i need to do and yet after 30 minutes of search I still do not know how to achieve it:

Say I have g=h+j-k+100

How do I evaluate g for h = 1, j=2, k=3?

I have found that if g=j+2, setting g(j)=g will do the trick for one variable only: g(1)=3, while g=j+2.

In mathematica it would be as simple as g/.{h->1,j->2,k->3}

This would come in very useful if you would want to evaluate function that has more than one variable.

Many thanks!

#2 Posted: 4/10/2014 5:46:56 PM

Alexander O. Melnik

127 likes in 494 posts.

Group: Moderator

Thank you ioan92! That is really what I needed.

Also what would be the best tutorial you can recommend on SMATH? Either English or Russian.

Thanks!

#3 Posted: 4/10/2014 5:49:40 PM

Martin Kraska

1222 likes in 2150 posts.

Group: Moderator

The FunctionsExtensions plugin provides the at() substitution function with special operator formatting. This exploits the symbolic storage of the expression in the variable g.

Martin Kraska Pre-configured portable distribution of SMath Studio: https://en.smath.info/wiki/SMath%20with%20Plugins.ashx

#4 Posted: 4/10/2014 5:54:11 PM

Alexander O. Melnik

127 likes in 494 posts.

Group: Moderator

That looks very interesting as well, will experiment. Thanks!

#5 Posted: 4/17/2014 10:36:20 AM

Alexander O. Melnik

127 likes in 494 posts.

Group: Moderator

Hi everyone!,

Not sure if this would be a bug but at() function does not seem to work while evaluating fuctions that include Min() or Max().

See workbook and photo attached.

Thanks!

2 users liked this post

Martin Kraska 4/17/2014 6:08:00 PM, Davide Carpi 4/19/2014 3:42:00 AM

#6 Posted: 4/17/2014 11:10:56 AM

Martin Kraska

1222 likes in 2150 posts.

Group: Moderator

Confirmed. This is bug of Min() and Max(). Apparently they always try to return a numeric result, regardles of what the optimization setting is. If they would return themselves with evaluated/preprocessed arguments, at() would work, as the example with max() shows.