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EL_108553943-Newcomer
3-Newcomer
November 12, 2023
Question

Need help to find a symbolic solution

  • November 12, 2023
  • 4 replies
  • 2758 views

Hi,

 

I'm having trouble finding a symbolic solution I can use in an excel sheet for later use.

I am aware that it's mabye impossible to find a symbolic solution.

EL_10855394_0-1699773925293.png

 

But I was hoping it was, And that you guys could help me?

 

All the values is >0

 

Erik

4 replies

W
Werner_E25-Diamond I
25-Diamond I
November 12, 2023

I guess you don't really excpect us to retype the forumula and you just forgot to attach your worksheet,

BTW, do you really mean cot(25) and not rather cot(25 deg) ?

And why would you finally use Excel to find the values and not Prime (maybe by using a numerical way like the "root" command?

My guess is that you will have no luck in finding a symbolic solution and if you really must use Excel instead of Prime then you may have to resort to the Excel numeric solver.

E
EL_108553943-NewcomerAuthor
3-Newcomer
November 12, 2023

I have attached the file now. And I came to think of it, that alle the values er >0.

 

Yeah it's 25deg.

 

I need to put the expression for c.uk into an Excel sheet, because i'm working on an general excel program. The simple program shall be used by my colleagues to determining the soil strength based on a given foundation size, force, depth and some of the other variables in the formula. Which is given based on the foundations size (the s.i factors).

It's looking something like this (in Danish).

 

EL_10855394_0-1699796725906.png

 

So all the variables have a known value depending on the foundations size, depth etc. So manually I could check the result for each 0,1 meters, but that will take for ever.. 

 

I hope that makes sense?

 

F
Fred_Kohlhepp23-Emerald I
23-Emerald I
November 12, 2023

First, let's observe that this is an unnecessarily complex equation. 

 

Define a variable 

 X = Fred_Kohlhepp_0-1699793740299.png

 

which can then become

 

s = (A+B+C)*X  or X = s/(A+B+C)

 

So now you have a much simpler equation to solve.  If the RHS is all known quantities this becomes some basic high school algebra!

 

 

W
Werner_E25-Diamond I
25-Diamond I
November 12, 2023
@Fred_Kohlhepp wrote:

...

If the RHS is all known quantities this becomes some basic high school algebra!

I guess that you had overlooked that the variable c.ud is also a factor of the last summand. 😞

L
LucMeekes23-Emerald IV
23-Emerald IV
November 12, 2023

There's no symbolic solution, the order of c.ud in your equation is too high:

LucMeekes_0-1699796021131.png

Try to numerically solve the equation, using the root() function in Prime.

 

Success!
Luc

E
EL_108553943-NewcomerAuthor
3-Newcomer
November 12, 2023

I haven't tried to use that before.

Is it possible to make that work if:

In a given situation and depth the values are as follows:

sigma is variable depending on the depth

N.i is constant

s.i is constant

gamma is variable

b is constant

q is variable depending on the depth.

H is constant

A is constant

V is constant

fi is constant

 

Not sure if that makes any difference 😉 

 

 

 

F
Fred_Kohlhepp23-Emerald I
23-Emerald I
November 13, 2023

Okay, why won't this work?  See the attached Prime 4 sheet.

E
EL_108553943-NewcomerAuthor
3-Newcomer
November 13, 2023

Thank you Fred.

Did you see that c.ud is also a variable in C?

EL_10855394_0-1699865304343.png

 

F
Fred_Kohlhepp23-Emerald I
23-Emerald I
November 13, 2023

AAGGH!

 

Sorry, old eyes missed that!

 

THAT'S why this won't work!!

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