supersix2

If you know anything about C programming please read on and see if you can help.

My version of Microsoft Visual C++ which was given to me by my school is missing files for the help section so I am unable to use that as a source. My friend reccomended these message boards to ask for help with programming.

Now to the question. I have to write a C program that finds the distance between 2 locations on the earth by using latitude and longitude. I have been given the equation all I need to do is to program it. My program already asks for and collects the data from the user. All I need to do now is write the equation.

Here is the equation I was given.

distance = 2r(arcsin)squareroot of(sin^2((first_latitude - second_latitude)/2) + cos(first_latitude)cos(second_latitude)sin^2((first_longitude - second_longitude)/2)

r being the radius of th earth in kilometers which was given to me.
and everthing after the words "squareroot of" being in a big square root symbol.

My problem is using trigonometry, powers, and squareroots in C. I haven't done math that advanced in C before. The extent of math I've used was basic arithmetic of + - * and /.

Any help will be greatly appreciated.

hrdwareguy

Well, I won't write the equation for you, but:

First, make sure to include the math.h header file, it will contain all the functions you need.

The functions are:
double cos(double x)
double sin(double x)
double asin(double x) /*arcsine of x*/
double pow(doublex, doubley) where x is raised to the y power.
double sqrt(double x)

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supersix2

So I have to write a separate function for each part of the equation?

Fallon

shouldn't have to
Might want to break it up a little bit though because it'd be quite a hefty assignment...

tekaweni

No, you can combine them into a single line, although that could involve an eye-popping amount of bracketting so you may want to split things up a bit. But you can use them inline -

double x, y, z;
z = (sin(x) + cos(y);

-or-

z = (2 * (sin(x) + cos(y));

..or as complicated as you need to get.

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supersix2

holy crap i think i did it
it works i'm happy

supersix2

crap..i just found a flaw...direction
there is an 80 degrees north and an 80 degrees south so now i have to go write even more lines of code...damnit



you can seriously find distance faster with a ruler and a map


stupid computer programming

tekaweni

- If it compiles, it must be right
- If it runs, ship it

Welcome to programming, dude :-)

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cheerios

now, if only compiling == running.

[wanders off muttering about functions returning null that shouldn't, and memory access runtime errors...]

juanvaldes

...if it breaks blame Microsoft.

supersix2

Ok I finally did it. My program now knows the difference between 80 degrees north and 80 degrees south as well as 80 degrees east and 80 degrees west.

I rule!

If anyone wants to see this insane piece of work let me know.

charliex

fwiw http://msdn.microsoft.com has pretty much all the VC documentation on it.