Population figures always refer to total population. Thus when we say 'fishermen' we are including fishwifes and all the little sprats as well.
Ed Stephan's original formulae appear at B14 and F41. His thesis is that doubling area doesn't double population for both countries and cities in realworld situations.
Variables come in three varieties:
Specific variables relate to individual countries and cities. Thus LAND specifies the land area of your country.
Relative variables are measured against an arbitrary standard. Thus for CLIM the standard is the English climate.
Fudge variables attempt to adjust results to fit with known historical facts. FARMFUDGE, for example, is used reflect England's maximum population in medieval times being about 5 million.
'Population' takes the variables entered and suggests a population. The 10^(LOG(LAND+COAST))^0.666 expression causes population to increase not in simple proportion to Area, as explained elsewhere.
FOOD attempts to estimate if enough food is available by population densities. It has a correction for imports and another (the ^1.5 power factor) for 'belt-tightening' and economising.
Below the Land Use section is IMPORT%, which allows food to be shipped in to cities. It does not provide extra food for peasants! Its main affect is to reduce the number of city people needing food (at CITYFEED).
WAGON is used to calculate CITYFOOD (D29), with the same 'belt-tightening' factor as FOOD. EFFICIENCY may well have a similar value to FOODUSE, but it is actually comparing the average peasant with a theoretical farmer growing crops only. As Efficiency rises so the number of peasants needed to provide food for the city decreases.
MDENS normally shows the density of population around the cities. However if there are no cities (at TLs 0 and 1) it changes to avoid a 'divide by zero' error.
RURDENSITY is the density of the whole non-urban population.
WILDENS is, like RURDENS, obtained by subtraction as the density of people living beyond the cities and not providing food for them.
MAXDENS is the maximum density possible with no unused land. It is used to calculate WILDERNESS (D24), the part of the country where the Monsters roam. Bold adventurers will also be interested in WILDGAP (B27), the distance to the next buxom village wench - er, essential source of supplies.
Also below the Warnings box are the Actual Land Use percentages - the ones you set were the Maximum possible values.
MARGIN in the Tech Table sets the amount of surplus food each farmer would have left over after feeding his family if he was only growing crops.
TLPOP refers to food production technology. Horse collars for example, introduced during the Middle Ages, enabled horses to be used for ploughing and transport instead of less efficient oxen.
The land around towns and cities is often the most fertile. Increase FARMLAND to cut down those woods and drain that marshland. CLANDUSE (D25) shows the result, and a Warning will light up if it goes over 100%.
Knowing the urban population we can calculate the land area needed for farmland to feed the cities. This is FARMAREA. Just above it is CITFISHAREA, space for fishermen to build cottages.
CITAREA is calculated from the EXP(K+(AR/9)*LN(POP/CCOUNT)) formula. As cities grow so the population density in the centre also grows (skyscrapers), but this is offset by factories and offices, the AR factor. The best way of understanding how this formula works is to play around with it.
To find the number of cities in a country, we start with the assumption that for each Big City there will be six small ones about one tenth the size, for each of these six smaller at one hundredth the size, and so on (this is not a Rule, if you want subsequently to stick say two 2,000 towns together to make a 4,000 one feel free). So the total urban population is going to be the Sum of the progression (P) + 6*(P/10) + 6*6*(P/100)...
The CityFudge Data Table takes account of how many terms we want in the progression, and unneeded terms are factored out (for mathmaticians the Sum to Infinity is 2.5).
CITAREA, the land occupied by cities formula, takes ARs from the table to the right and applies them to each city size. As you will be aware from trying out a single city changing ARs affects CITAREA a lot - you are deciding how much space factories and offices will take up.
If there are no Cities CITYDENS takes a nominal value of 10,000 for the benefit of Fishermen, who still need land for their cottages.
I ought perhaps to justify VILGAP. It is a good rule-of-thumb in England that settlements are a mile apart, given useable land between them. The MDENS:WILDDENS ratio should give an indication of how much rural areas differ from such well-populated areas, and that's what WILDGAP uses. See the 1086 settings for more on this. At present City gives a village size of 128, which is not unreasonable.
The spreadsheet is calibrated around TL3, so you are strongly advised to leave TL3 values alone in the Tech Table, which is why they are protected. If you want to make changes to TL3, make them elsewhere. The other Tech Levels will be relative to TL3 and are open to debate.
(1) URBAN TOO HIGH. There are not enough farmers to feed the cities.
(2) CITY FOOD SHORTAGES? Watch out for bread riots.
(3) FOOD SHORTAGE. Riots everywhere!
(4) URBAN OVERPOPULATION. There is no room left for cities and their associated farming land.
(5) OVERPOPULATION. There were too many adventurers chasing buxom village wenches last year.
(6) RURAL FOOD SHORTAGES? Watch out for peasant revolts.
(7) FARMLAND TOO HIGH. There cannot be more than 100% farmland around cities.
(8) LAND USE MAX TOO HIGH! There cannot be more than 100% useable land.