Forum Discussion
Sigma Formula for Carbon Estimation
The data that you provide in the Excel file is insufficient.
The notation
implies that Drr, Apa and Grr are 3-dimensional arrays, and C and Csf are 1-dimensional arrays.
The sigma formula says that we sum Drr*Apa*(C-Cnf) + Grr*Apa*(C-Csf) for each i, j and k -- that is, for each cell identified by each i,j,k in Drr, Apa and Grr and by each corresponding i in C and Csf.
But you only provide only one value of each in columns B:D, to namely:
| Drr i,j,k | Peat swamp | 0.20 |
| Sec peat swamp | 0.10 | |
| Riparian | 1.70 | |
| Sec riparian | 0.50 | |
| Grr i,j,k | Peat swamp | 0.13 |
| Sec peat swamp | - | |
| Riparian | 0.01 | |
| Sec riparian | - | |
| Apa i,j,k | Peat swamp | 30.00 |
| Sec peat swamp | 23.00 | |
| Riparian | 713.00 | |
| Sec riparian | 58.00 | |
| Ci | Peat swamp | 147.00 |
| Sec peat swamp | 147.00 | |
| Riparian | 174.00 | |
| Sec riparian | 174.00 | |
| Csfi | Peat swamp | 104.00 |
| Sec peat swamp | 104.00 | |
| Riparian | 52.00 | |
| Sec riparian | 52.00 |
If i goes from 1 to p, and j goes from 1 to q, and k goes from 1 to r, you need to provide p*q*r data for each of Drr, Apa and Grr and p data for each of C and Csf.
You might present Drr, Apa and Grr as p-by-q arrays of data repeated r times (a total of p*r rows). We can derive p from the size of C and Csf.
Otherwise, you need to tell us what p, q and r are.
Hi, I'm so sorry for this late reply. Well, I referred to the reference document which provides a table like below:
'Drr' and 'Grr' for each i,j,k
'Apa' value for each i,j,k
And the expected result should be like below (highlighted number):
What I tried in the excel file was to obtain that result. I also want to confirm, does the formula that I wrote in the file is correct?
According to this screenshot, the Drr and Grr values are percentages, so their values in your sample workbook are a factor 100 too large.
The value you want is the sum of the EBLs for the four forest types.
Your screenshots do not show the C, Cnf and Csf values, so I cannot check the outcome of your formula against that in the last screenshot.
Hi Hans, thank you for still interested in this topic. Really appreciate it. Value for C, Cnf, and Csf provided below:
