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Finding Root

ptc-5029428
1-Newbie

Finding Root

Dear All,

Appreciate an assisstance from someone in this community.

I'm trying to figure out where did i dont wrong as my method of finding a root for my problem did not ended well.

suppose two equations if both of them subtracted each other will end up zero or same value.

however in my case it does not.

for more clear picture on what do i really meant, here is the mathcad that i'm working on.

Appreciate somebody could assist me on resolving it.

Thanx in advance

5 REPLIES 5

I am not sure what you are expecting to get with your calculation of Sui.min.

You are looping through all depths ("i"), calculating 17 times a value for Sumax and the result of the whole procedure is the value of Sumax for the last depth.

Consequently the following check shows the "correct" result:

02.02.png

I don't understand why you expect am equal result with your interpolated depth and the formula with missing eta.e.

What do you expect to get for Sui.min? A vector with 17 elements for every depth? This could easily be done.

Dear Werner,

maybe i'm not explaining it well in my earlier msg. Sorry my mistake.

Anyway fyi:

1) The tabulated data with 17 rows of depth are data provided from my client. It is obtain from the survey which give the relation between depth and soil strength.

2) after Weff is obtained (the submerged weight), i need to estimate till what depth does my pipe sink.

3) since (by refering to the table) the soil strength depends on the depth as well therefore the equation that i state is implicit and needs to be solved iteratively.

4) so my interpretation is that by subtracting LHS and RHS will give a product of zero, then both the Sui.min and the Ass_Depth can be obtained. Just that i'm not doing it correctly in mcad.

Hope it clear up the confusion.

Regards

-Akmal-

Could it be you are searching for something like the attached?

Dear Werner,

Its brilliant. This is the answer i'm looking for.

Sorry some wrong information i've summarise earlier whereby it is for the medium category (i mean the Zi1=0.535m and SU1=2.55kPa)

Thank you very2x much.

You are welcome.

Depending on the precison you need you may also consider to replace the simple linear interpolation by something else. See attached sheet for cubic splines interpolation and a couple of approximations (polynomial, exponential. logistic regression). The approximations don't do that well but if you have an idea what kind of function your Soil.max(depth) could be, you might try genfit().

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