lsolve with known values

[MachinaMan]

Hi,

I am trying to solve a linear system of equations with lsolve but there are certain values of the solution that are known.

How can I do this?

Thanks

 

[rjw57]

Maybe I'm oversimplifying this, but since you seem to be saying that you know one of the coefficients to the system of equations, just specify that as an equality prior to using lsolve to obtain the solution.

rjw57

 

[GregLocock]

First thought:

since lsolve is a linear solution to a perfectly conditioned problem then it doesn't matter if you already know one of the answers, it should come out the same again.

Second thought: substitute your known value into the equations and then tidy them up. This will give you a smaller matrix to solve

Cheers

Greg Locock

 

[MachinaMan]

Hi

I should have specified this in my first post.

I want to solve Kx=F for x so

x:=lsolve(K,F)

very simple, but I have restrictions for x, ie. x1=0 and x5=3.5. How do I specify this?

I have also tried the Given/Find block but it only spits out my initial guesses no matter what they are.

any help would be great.

Thanks

René