# What does this do?

## What does this do?

I'm just curious.

#include <math.h>

double dist(double x1,double y1,double x2,double y2) {

return sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));

}

double slope(double x1,double y1,double x2,double y2) {

return(atan((y2-y1)/(x2-x1)));

}

void main(int argc,char **argv) {

struct {

double x;

double y;

double speed;

double new_speed;

double dist;

} a,b,c,you;

double dist_a, dist_b,dist_c;

double raptor_accel=4.0;

double you_dir=30.0;

double interval=0.001;

double time=0.0000;

double grad;

double pi = 3.1415926535897932384626433832795;

int i;

double best_dir=0;

double best_time=0.0;

char best_got;

char got;

for (you_dir=32;you_dir<33;you_dir += 0.001) {

you.x = you.y = 0.0;

a.x = 0; a.y = 11.547005383792515290182975610039;

b.x = -10;b.y = -5.7735026918962576450914878050196;

c.x = 10;c.y=-5.7735026918962576450914878050 196;

a.dist = b.dist = c.dist = you.dist = 0.0;

a.speed = b.speed = c.speed = 0.0;

a.new_speed = b.new_speed = c.new_speed = 0.0;

you.speed = 6.0;

time = 0;

while (1) {

dist_a = dist(a.x,a.y,you.x,you.y);

dist_b = dist(b.x,b.y,you.x,you.y);

dist_c = dist(c.x,c.y,you.x,you.y);

/*

printf("you at at (%f,%f) -travelled %f\n",you.x,you.y,you.dist);

printf("raptor a at (%f,%f) ( distance %f) - travelled %f\n",a.x,a.y,dist_a,a.dist);

printf("raptor b at (%f,%f) ( distance %f) - travelled %f\n",b.x,b.y,dist_b,b.dist);

printf("raptor c at (%f,%f) ( distance %f) - travelled %f\n",c.x,c.y,dist_c,c.dist);

*/

if (dist_a == 0.0 ) {

printf("Raptor a got you in %f secs!\n",time);

break;

}

if (dist_b == 0.0 ) {

printf("Raptor b got you in %f secs!\n",time);

break;

}

if (dist_c == 0.0 ) {

printf("Raptor c got you in %f secs!\n",time);

break;

}

time += interval;

/* You Move first */

you.x += you.speed*interval*cos(pi*you_dir/180)

;

you.y += you.speed*interval*sin(pi*you_dir/180)

;

you.dist +=you.speed*interval;

/* Accelerate the raptors */

a.new_speed += raptor_accel*interval;

b.new_speed += raptor_accel*interval;

c.new_speed = b.new_speed;

if (a.new_speed > 10.0 )

a.new_speed = 10.0;

if (b.new_speed > 25.0 )

c.new_speed = b.new_speed = 25.0;

/*

printf("a raptor_speed is now %f\n",a.new_speed);

printf("b and c raptor_speed is now %f\n",b.new_speed);

*/

/* Raptor a moves */

if ( a.speed*interval > dist_a ) {

/*

printf("Raptor a will get you within this interval time is %f secs!\n",time);

*/

got = 'a';

break;

}

grad = slope(a.x,a.y,you.x,you.y);

a.x += (a.new_speed+a.speed)/2*interval*cos(g rad);

a.y += (a.new_speed+a.speed)/2*interval*sin(g rad);

a.dist += (a.new_speed+a.speed)/2*interval;

a.speed = a.new_speed;

/* Raptor b moves */

if ( b.speed *interval > dist_b ) {

/*

printf("Raptor b will get you within this interval time is %f secs!\n",time);

*/

got = 'b';

break;

}

grad = slope(b.x,b.y,you.x,you.y);

b.x += (b.new_speed+b.speed)/2*interval*cos(g rad);

b.y += (b.new_speed+b.speed)/2*interval*sin(g rad);

b.dist += (b.new_speed+b.speed)/2*interval;

b.speed = b.new_speed;

/* Raptor c moves */

if ( c.speed*interval > dist_c ) {

/*

printf("Raptor c will get you within this interval time is %f secs!\n",time);

*/

got = 'c';

break;

}

grad = slope(c.x,c.y,you.x,you.y);

if ( c.x > you.x ) {

c.x -= (c.new_speed+c.speed)/2*interval*cos(g rad);

c.y -= (c.new_speed+c.speed)/2*interval*sin(g rad);

}

else {

c.x += (c.new_speed+c.speed)/2*interval*cos(g rad);

c.y += (c.new_speed+c.speed)/2*interval*sin(g rad);

}

c.dist += (c.new_speed+c.speed)/2*interval;

c.speed = c.new_speed;

}

if ( time > best_time ) {

best_time = time;

best_dir = you_dir;

best_got = got;

}

}

printf("Best time is %f best dir is %f got by raptor %c\n",best_time,best_dir,best_got);

}

#include <math.h>

double dist(double x1,double y1,double x2,double y2) {

return sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));

}

double slope(double x1,double y1,double x2,double y2) {

return(atan((y2-y1)/(x2-x1)));

}

void main(int argc,char **argv) {

struct {

double x;

double y;

double speed;

double new_speed;

double dist;

} a,b,c,you;

double dist_a, dist_b,dist_c;

double raptor_accel=4.0;

double you_dir=30.0;

double interval=0.001;

double time=0.0000;

double grad;

double pi = 3.1415926535897932384626433832795;

int i;

double best_dir=0;

double best_time=0.0;

char best_got;

char got;

for (you_dir=32;you_dir<33;you_dir += 0.001) {

you.x = you.y = 0.0;

a.x = 0; a.y = 11.547005383792515290182975610039;

b.x = -10;b.y = -5.7735026918962576450914878050196;

c.x = 10;c.y=-5.7735026918962576450914878050 196;

a.dist = b.dist = c.dist = you.dist = 0.0;

a.speed = b.speed = c.speed = 0.0;

a.new_speed = b.new_speed = c.new_speed = 0.0;

you.speed = 6.0;

time = 0;

while (1) {

dist_a = dist(a.x,a.y,you.x,you.y);

dist_b = dist(b.x,b.y,you.x,you.y);

dist_c = dist(c.x,c.y,you.x,you.y);

/*

printf("you at at (%f,%f) -travelled %f\n",you.x,you.y,you.dist);

printf("raptor a at (%f,%f) ( distance %f) - travelled %f\n",a.x,a.y,dist_a,a.dist);

printf("raptor b at (%f,%f) ( distance %f) - travelled %f\n",b.x,b.y,dist_b,b.dist);

printf("raptor c at (%f,%f) ( distance %f) - travelled %f\n",c.x,c.y,dist_c,c.dist);

*/

if (dist_a == 0.0 ) {

printf("Raptor a got you in %f secs!\n",time);

break;

}

if (dist_b == 0.0 ) {

printf("Raptor b got you in %f secs!\n",time);

break;

}

if (dist_c == 0.0 ) {

printf("Raptor c got you in %f secs!\n",time);

break;

}

time += interval;

/* You Move first */

you.x += you.speed*interval*cos(pi*you_dir/180)

;

you.y += you.speed*interval*sin(pi*you_dir/180)

;

you.dist +=you.speed*interval;

/* Accelerate the raptors */

a.new_speed += raptor_accel*interval;

b.new_speed += raptor_accel*interval;

c.new_speed = b.new_speed;

if (a.new_speed > 10.0 )

a.new_speed = 10.0;

if (b.new_speed > 25.0 )

c.new_speed = b.new_speed = 25.0;

/*

printf("a raptor_speed is now %f\n",a.new_speed);

printf("b and c raptor_speed is now %f\n",b.new_speed);

*/

/* Raptor a moves */

if ( a.speed*interval > dist_a ) {

/*

printf("Raptor a will get you within this interval time is %f secs!\n",time);

*/

got = 'a';

break;

}

grad = slope(a.x,a.y,you.x,you.y);

a.x += (a.new_speed+a.speed)/2*interval*cos(g rad);

a.y += (a.new_speed+a.speed)/2*interval*sin(g rad);

a.dist += (a.new_speed+a.speed)/2*interval;

a.speed = a.new_speed;

/* Raptor b moves */

if ( b.speed *interval > dist_b ) {

/*

printf("Raptor b will get you within this interval time is %f secs!\n",time);

*/

got = 'b';

break;

}

grad = slope(b.x,b.y,you.x,you.y);

b.x += (b.new_speed+b.speed)/2*interval*cos(g rad);

b.y += (b.new_speed+b.speed)/2*interval*sin(g rad);

b.dist += (b.new_speed+b.speed)/2*interval;

b.speed = b.new_speed;

/* Raptor c moves */

if ( c.speed*interval > dist_c ) {

/*

printf("Raptor c will get you within this interval time is %f secs!\n",time);

*/

got = 'c';

break;

}

grad = slope(c.x,c.y,you.x,you.y);

if ( c.x > you.x ) {

c.x -= (c.new_speed+c.speed)/2*interval*cos(g rad);

c.y -= (c.new_speed+c.speed)/2*interval*sin(g rad);

}

else {

c.x += (c.new_speed+c.speed)/2*interval*cos(g rad);

c.y += (c.new_speed+c.speed)/2*interval*sin(g rad);

}

c.dist += (c.new_speed+c.speed)/2*interval;

c.speed = c.new_speed;

}

if ( time > best_time ) {

best_time = time;

best_dir = you_dir;

best_got = got;

}

}

printf("Best time is %f best dir is %f got by raptor %c\n",best_time,best_dir,best_got);

}

**Daimon**- Human
- Posts : 9

Join date : 2010-11-13

Age : 21

## Re: What does this do?

it's a C/C++ program making fun of an xkcd comic. It basically solves the problem here:

XKCD 135

While whoever made it is probably decent in math, they over-thought their precision. There is really no use to have decimals to that precision, because it's doubtful that they are that accurate.

XKCD 135

While whoever made it is probably decent in math, they over-thought their precision. There is really no use to have decimals to that precision, because it's doubtful that they are that accurate.

**Break**- Student
- Posts : 128

Join date : 2010-09-28

Age : 29

Location : Texas

## Re: What does this do?

So, what's the answer to the problem? XD

**Daimon**- Human
- Posts : 9

Join date : 2010-11-13

Age : 21

## Re: What does this do?

Do the math, I'm too busy to work out a problem for you.

**Break**- Student
- Posts : 128

Join date : 2010-09-28

Age : 29

Location : Texas

## Re: What does this do?

I thought it gave the answer @_@

**Daimon**- Human
- Posts : 9

Join date : 2010-11-13

Age : 21

## Re: What does this do?

i don't have a c/c++ compiler on this computer, and since i never use it it wouldn't be worth my time to install one. Go install Visual Studio and compile the code if you want to see the exact answer from the program

**Break**- Student
- Posts : 128

Join date : 2010-09-28

Age : 29

Location : Texas

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