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16-Pearl

## FIND issue

Hello,

can anybody help me to find out why this FIND doesn't work?

Raiko

1 ACCEPTED SOLUTION

Accepted Solutions
24-Ruby V
(To:Raiko)

You have not defined theta and delta.

theta does not depend on rho1, so you can calculate it directly in front of the solve block.

You then have to provide a guess for delta and let the solve block solve for delta, too.

As delta and rho are of different dimensions you have to assign the result of find to a 2x1 vector as Mathcad can't display arrays with elements of different dimensions (in your case kg/m^3 and unitless).

4 REPLIES 4
24-Ruby V
(To:Raiko)

You have not defined theta and delta.

theta does not depend on rho1, so you can calculate it directly in front of the solve block.

You then have to provide a guess for delta and let the solve block solve for delta, too.

As delta and rho are of different dimensions you have to assign the result of find to a 2x1 vector as Mathcad can't display arrays with elements of different dimensions (in your case kg/m^3 and unitless).

16-Pearl
(To:Werner_E)

Thank you Werner.

However, the solution can't be right as it returns a negative density. When I try to force it to be positive by using rho1 > 0 and delta > 0 then the solve block doesn't converge. any idea how to remedy this?

Raiko

16-Pearl
(To:Werner_E)

Ignore my last request. I found my error. Thanks for the help.

Raiko

24-Ruby V
(To:Raiko)

I already guessed that a negative result is not what you are after, but I was not able to spot an obvious error in your equation.

BTW, as you already have defined theta=T1/Tk, why don't you use theta on the LHS of your equation instead of T1/Tk and Tk/T1 ?

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