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Thread Subject:
Question about solve

Subject: Question about solve

From: oversky

Date: 22 Dec, 2011 08:00:14

Message: 1 of 3

>> clear all
>> syms f n R1 R1 t
>> solve('1/f = (n-1)(1/R1-1/R2-n/(n-1)*t/R1/R2)','t')
Warning: Explicit solution could not be found.
> In solve at 81
ans =
[ empty sym ]

I tried to solve the LensMaker's equation for t as above,
but it didn't find the answer.

Do I use solve in the wrong way?

This equation should have explicit solution as in the following link.
http://is.gd/3E62xg

Subject: Question about solve

From: Roger Stafford

Date: 22 Dec, 2011 18:10:09

Message: 2 of 3

oversky <mailcwc@gmail.com> wrote in message <273d2ac5-844d-4b65-9833-5f1a98178a76@37g2000prc.googlegroups.com>...
> >> solve('1/f = (n-1)(1/R1-1/R2-n/(n-1)*t/R1/R2)','t')
- - - - - - - -
  Apparently you have omitted the '*' multiplication operator following the first 'n-1' in your expression. That makes the expression invalid. Otherwise it should be easily solvable.

Roger Stafford

Subject: Question about solve

From: Che-Wei

Date: 23 Dec, 2011 01:34:03

Message: 3 of 3

On 12月23日, 上午2時10分, "Roger Stafford"
<ellieandrogerxy...@mindspring.com.invalid> wrote:
> oversky <mail...@gmail.com> wrote in message <273d2ac5-844d-4b65-9833-5f1a98178...@37g2000prc.googlegroups.com>...
> > >> solve('1/f = (n-1)(1/R1-1/R2-n/(n-1)*t/R1/R2)','t')
>
> - - - - - - - -
>   Apparently you have omitted the '*' multiplication operator following the first 'n-1' in your expression.  That makes the expression invalid.  Otherwise it should be easily solvable.
>
> Roger Stafford
Thanks. I first tested this equation with f, and it went without
problem.
Then, I changed f to t. That's why I assumed the equation was input
correctly.

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