EmilSoleymani
commented
2 years ago The following code opens input and output file. It reads the first line (the title) and copies it into the output file: https://github.com/smiths/vdisp/blob/0ee717473b63e17b6b0152c12a2181bdb9aff6e5/fortran_src/vdisp.for#L6-L9
The following code reads the second line from the input file. It parses NPROB, NOPT, NBPRES, NNP, NBX, NMAT, DX. It first prints NPROB, NNP, NBX, NMAT, DX. NOPT and NBPRES are used to determine soil type and foundation type. The if statements select what FORMAT string to print from lines 104-114:
https://github.com/smiths/vdisp/blob/0ee717473b63e17b6b0152c12a2181bdb9aff6e5/fortran_src/vdisp.for#L15-L24
https://github.com/smiths/vdisp/blob/0ee717473b63e17b6b0152c12a2181bdb9aff6e5/fortran_src/vdisp.for#L104-L114
The following code calculates DEPF and DEPPR and prints them with format strings on lines 115 and 116 : https://github.com/smiths/vdisp/blob/0ee717473b63e17b6b0152c12a2181bdb9aff6e5/fortran_src/vdisp.for#L26-L29 https://github.com/smiths/vdisp/blob/0ee717473b63e17b6b0152c12a2181bdb9aff6e5/fortran_src/vdisp.for#L115-L116
Here is a dictionary I have come up with so far for these code snippets, based on the format strings:
- NPROB: Number of problems
- NOPT = Number of option? Model Number?
0: Consolidation Swell Model 1: Leaonards and Frost Model 2: Schmertmann Model 3: Collapsible Soil 4: Elastic Soil
- NBPRES: B = Base? Number of bases present?
1: Rectangular Slab Foundation 2: Long Continuous Strip Foundation
- NNP: Number of Nodal Points
- NBX: Number of Nodal Points at Bottom of Foundation
- NMAT: Number of Different Soil Layers
- DX: Increment depth (delta x?)
- DEPF: Depth of Foundation
DEPF = DX*FLOAT(NBX-1)
- DEPPR: Total Depth Of Soil Profile
DEPPR = DX*FLOAT(NNP-1)
Having a hard time following the specifics of this part, however I understand it prints out the first table which is Number of Soil vs. Element. It prints each entry with format 32 on line 118. At the end it prints the header for the next table, which shows the specific gravity, water content and void ratio for each material: https://github.com/smiths/vdisp/blob/0ee717473b63e17b6b0152c12a2181bdb9aff6e5/fortran_src/vdisp.for#L30-L49
Line 32 just writes the header of the table that is about to be printed. My problem in understanding comes from IE(N,1) on line 33. I understand that IE(NQ,1) is defined in a COMMON block on line 2 in order to be accessed in other subroutines, however I don't understand what it is - a function? a variable? what are we passing into it? how are we reading from it if I can't find its definition anywhere in the document? However, I do understand what is happening, just now HOW it's happening. In VDIN.DAT we have:
1 1
12 2
16 2This is read by the code snippet, and in a table fills in all the intermediate values ( > 1 and < 12 is 1, > 12 and < 16 is 2) like so:
ELEMENT NUMBER OF SOIL
1 1
2 1
3 1
4 1
5 1
6 1
7 1
8 1
9 1
10 1
11 1
12 2
13 2
14 2
15 2
16 2
Now after printing this, and the header for the next table ( MATERIAL SPECIFIC GRAVITY WATER CONTENT,% VOID RATIO ), the following code enumerates the materials (number of different soil layers) and lists each ones Specific gravity, water content and void ratio: https://github.com/smiths/vdisp/blob/0ee717473b63e17b6b0152c12a2181bdb9aff6e5/fortran_src/vdisp.for#L51-L53
Thus, we can deduce the following naming:
- M: Material
- G(M): Specific gravity of material M
- WC(M): Water content of material M
- EO(M): Void ratio of material M
smiths
This matches formula (3-21) on page 28 of the settlements book perfectly. In the picture they are finding change in void ratio, but changing that to (final void ratio - initial void ratio) and moving the initial to RHS produces the calculations on line 164 exactly
The inequality on the lines below the equation explain the 
In the previous comment ( lines 159-165 ) we performed the calculations for Step 6 of this procedure. Examining the lines that come right after, lines 167-173, we see a similar structure to the formula in Step 7:
Note that the numerator here is what we calculate in Step 6 which was covered in the previous comment.
This makes sense since gamma_w could be abbreviated to GAW. The textbook gives a version accurate to 3 decimal places, while the code uses the slightly more accurate 0.03125. 
The book gives a complicated breakdown of each variable and I had to go all over the book looking for intermediate formulas. I took notes on everything I found and they are available for download in the following pdf:
Here are the paragraphs on page 4 of the settlements textbook which refer to the unit weight of water with the units tsf. I too was confused upon reading this.
To create new code, we need to figure out what the old code does. We should go through the FORTRAN CODE and say what each "chunk" of code does. I think we can use the features of GitHub to make this relatively easy to do. For instance, we can do something like:
Code to initialize program, declare variables for PP, G and WC, and open files: https://github.com/smiths/vdisp/blob/0ee717473b63e17b6b0152c12a2181bdb9aff6e5/fortran_src/vdisp.for#L1-L9
We should probably also keep a dictionary of variable names and their meaning. For instance, I don't know what PP, G and WC are. :smile: I feel like the W means water. G might be specific gravity? We'll figure it out.