Hi,

I'm new to SMath but familiar with MathCAD. I'm used to solving systems of equations using "Solve" and "Find" in MathCAD and wondering how to do the same thing in SMath. So far I haven't seen any posts addressing this specifically. The mass balance I'm currently playing around with is displayed below trying to solve for D & E. Any help is appreciated. Thank you.

F:=175000

F.ia:0.15
D.ia:=0.9034
E.ia:=0.0005

F:=(D*D.ia+E*E.ia)/F.ia

res:=solve(F=D+E,D) <-- Boolean Equals

Hello,

It seems you've been missing variable "E". Define it before the solve() and see what will be the result.

Regards,
Radovan


[MATH=eng]F:175000[/MATH]

[MATH=eng]F.ia:0.15[/MATH]

[MATH=eng]D.ia:0.9034[/MATH]

[MATH=eng]E.ia:0.0005[/MATH]

[MATH=eng]F:{D*D.ia+E*E.ia}/F.ia[/MATH]

[MATH=eng]E:1[/MATH] //this was missing

[MATH=eng]res:solve(F≡D+E,D)[/MATH]

[MATH=eng]res=0.1984[/MATH]


P.S. Search the Forum and Wiki for solve() and roots() functions

Radovan,

Thank you for a quick response. However, what I'm looking to do is solve a system of two equations for two variables:

F=(D*D.ia+E*E.ia)/F.ia
&
F=D+E

As long as everything but D&E is defined, D&E can be solved for.

Is there a command in SMath to solve x equations simultaneously for x variables? Thank you again for your help.

Hello,

For the system of equations you can try roots()


[MATH=eng]roots(mat(F-{D*D.ia+E*E.ia}/F.ia,F-D-E,2,1),mat(D,E,2,1))=mat(28976.0771,1.4602*10^5,2,1)[/MATH]


If fails, try with guess values
Guess values:


[MATH=eng]D0:1[/MATH]
[MATH=eng]E0:1[/MATH]


[MATH=eng]res:roots(mat(F-{D*D.ia+E*E.ia}/F.ia,F-D-E,2,1),mat(D,E,2,1),mat(D0,E0,2,1))[/MATH]


[MATH=eng]res=mat(28976.0771,1.4602*10^5,2,1)[/MATH]


Checking


[MATH=eng]mat(F-{el(res,1)*D.ia+el(res,2)*E.ia}/F.ia,F-el(res,1)-el(res,2),2,1)=mat(0,-5.0331648*10^{-10},2,1)[/MATH]

Regards,
Radovan