Doing The Math

[+buteo]

I NEED HELP WITH MY MATH.WHAT IS THE DISTANCE IN FEET BETWEEN 44.50.100 AND44.50.900.LIKEWISE WHAT WOULD BE THE DISTANCE BETWEEN 44.50.100 AND 44.51.100.THANKS FOR THE MATH LESSON

[+Chuy!]

Using my MapSource:

.921 miles between 44.50.100 & 44.50.900;

1.15 miles between 44.50.100 & 44.51.100.

 

For feet, I'll let you convert it using conversion.com or other website of your choice.

[+TotemLake]

And now for an netiquette lesson...

 

Please don't use all CAPS when posting. It's considered shouting to the eyes.

[+RocketMan]

GeoCalc does the work for you! There is no math needed. RM

 

Edit - This seems appropriate: “Give a man a fish; you have fed him for today. Teach a man to fish; and you have fed him for a lifetime”

Edited August 14, 2005 by Rocket Man

[+WizCreations]

Another good site to use is http://boulter.com/gps/distance

 

What puzzle cache are you trying to cheat on?

[+Tidalflame]

The actual math is rather complicated. I believe there's something on Markwell's site on how to do it.

[+EScout]

We assume you are talking about latitude, because if you are talking about longitude, it depends where you are.

This is another thing that is easily done in your GPSr, by entering the waypoints and inserting them into a route and reading the distance.

For more precision, use a computer or PDA program.

Assuming you are talking about latitude, I used the Palm program Navigate, great circle calculation and got .92070 mile and 1.15087 miles.

[+Muddler]

If you have mapping software you can plot points on the map and measure the distance between the points. In south Alabama I have found the the Latitude lines are approximately 0.12 miles per 0.1 minutes change. Longitude on the other-hand is 0.1 miles per 0.1 minutes. I use these as rules of thumb down here. Where you live will be slightly different.

 

Latitude will stay the same as you move N & S, the lines are equidistant apart. Longitude on the other hand will decrease as you move north, the lines move closer together as you move away from the equator and toward the poles

 

Cheers

 

Muddler

[+The Saints]

Rocket man,

I have a quote for you similar to yours:

"Build a man a fire and he stays warm for a night. Set a man on fire and he stays warm for the rest of his life."

Just a joke

[+Joypa]

I just use the rough estimate of 5 feet for every .001 coordinate minute. So .800 would be approximately 800x5= 4000 feet. This is ballpark stuff.

[+edscott]

interesting.. I am just working this out for myself so I can do more GPS-less multis without returning home to download a new map showing the location of each part. At 40 degrees N Latitude a 40 nn.1nn X -75 nn.1nn square is roughly 150 x 185 meters. I've only done two multis this way so far but have another one downloaded to try soon. Of course if the stages are too far apart and go off my original map then I am screwed. So far I've done the math in my head.. but I may need to start carrying a calculator which sort of goes against my no electronic help past...

[+Firestone]

The Great Circle Calculator

 

Here is a really good web site for getting the distance between two sets of coordinates, or getting a new set of coordinates from a known set, knowing a bearing and distance. The results come from Great Circle calculations. The advantage this site has over most is the level of accuracy it allows.

 

Great Circle Calculator

 

By the way, I agree with JoyPa, above, that in the field use 5 or 6 feet for each 0.001 minutes offset in latitude or longitude. (I use 6'.) If there is an offset in both, I square the two distances, add them together and then take the square root of the sum. (Remember Pythagoras?) This all sounds like a complicated process to do on the fly, but remember, you do not have to be that acurate if you are already that close.

[+fizzymagic]

The advantage this site has over most is the level of accuracy it allows.

The site has exactly the same accuracy as any other site that uses Vincenty's method for calculating distance. What gave you the impression that it was more accurate?

 

It's cool that it does it in Javascript, though. I like that.

[+Firestone]

The reason I said that it provides more accuracy is that it allows you to input more decimal places than many sites allow. For example, you can work with ten thousandths of a second. I agree, it has nothing to do with the algorithm itself.

[+fizzymagic]

The reason I said that it provides more accuracy is that it allows you to input more decimal places than many sites allow.

Ah. You mean precision, not accuracy. It's not always obvious, but most sites allow you to enter much higher precision than integral seconds.

 

The input precision problem is a big issue for using your GPSr to do these calculations; most of them won't let you enter distances with enough precision to do useful projections over 0.1 mile. That can be quite frustrating in the field!

[+Firestone]

The more precision you are allowed, the more accuracy you have.

[+fizzymagic]

The more precision you are allowed, the more accuracy you have.

Not true. Accuracy and precision are very different concepts.

 

Here is one explanation.

 

Precision is the number of significant digits in a calculation.

 

Accuracy is the degree to which the calculated number corresponds to the true number.

 

In this case, the accuracy of the calculations depends on the algorithm being used and the assumptions made about the shape of the Earth. The Vincenty algorithm, which is used by the page you pointed to, gives the most accurate distance measurement on a perfect ellipsoid. If the Earth were a perfect ellipsoid, Vincenty's algorithm would give distance measurements accurate to a few mm over 10,000 miles. Pretty impressive.

 

However, the Earth is not a perfect ellipsoid; it is bumpy, both from topography and from the geoid (the variation in the average shape of the Earth as a result of gravitational anomalies). So the realistic accuracy of these distance measures is probably more like a part in 10^5 or so, about 10 meters over a distance of 1000 km. Still impressive, but now the precision possible is much greater than the accuracy.

 

Using more significant digits in your input is not going to give better output accuracy than the algorithm can provide. It is just a fact of life. You can specify a projection where you travel 162.00239828732 miles, and the algorithm may give you very precise output, but the accuracy will be exactly the same as if you specified that you traveled 162.002 miles.

[+AtoZ]

The more precision you are allowed, the more accuracy you have.

Not true. Accuracy and precision are very different concepts.

 

Here is one explanation.

 

Precision is the number of significant digits in a calculation.

 

Accuracy is the degree to which the calculated number corresponds to the true number.

 

Acutally precision is how repeaable the answer is not the number of digits. Look at it like someone firing a bow and arrow they may not hit the bulls eye but they have a tight grouping of the arrows so they are precise but not accurate. This is the scientific view.

 

The nuber of signfinate figures was whtt fuzzylogic was acutally refering to as precision.

 

cheers

[+sbell111]

The more precision you are allowed, the more accuracy you have.

Not true. Accuracy and precision are very different concepts.

 

Here is one explanation.

 

Precision is the number of significant digits in a calculation.

 

Accuracy is the degree to which the calculated number corresponds to the true number.

 

Acutally precision is how repeaable the answer is not the number of digits. Look at it like someone firing a bow and arrow they may not hit the bulls eye but they have a tight grouping of the arrows so they are precise but not accurate. This is the scientific view.

 

The nuber of signfinate figures was whtt fuzzylogic was acutally refering to as precision.

 

cheers

Hmmm, its a math question. I'll go with Fizzy.

[+fizzymagic]

Acutally precision is how repeaable the answer is not the number of digits.

That is the precision of a measurement. In this thread, we are talking about the precision of calculations.

[+Thrak]

Give a man a fish and you will feed him for one day.

 

Teach a man to fish and he'll sit in a boat and drink beer for the rest of his life.