Write a program called rotate$\_$point that solicits an x and y coordinate representing a point and an angle in degrees and then displays the point that would result from rotating the given one about the origin by the given angle.

Example runs:

$..$hing$/$cyb$126\%./$rotate$\_$point$$

Please enter an x coordinate: $30$

Please enter an y coordinate: $1$

Please enter the number of degrees to rotate by: $45$

The result is $(20\mathrm{.}506097,21\mathrm{.}920310)$

$$Formulae:

Degrees to radians

$180$degrees

Rotation formulae

xnew$=$xcos$($$)-$ysin$($$)$

ynew$=$xsin$($$)+$ycos$($$)$

Notes, hints, and reminders:

Math

The library needs to be included to access the sin$()$ and cos$()$ functions as well as the M$\_$PI constant

When you compile your program with gcc$,$ don't forget to add the $"-$lm$"($link math$)$ flag to the command

If you get an error when compiling that says "undefined reference to sin$()"$ move the $"-$lm$"$ flag to a different position in the gcc command; if you had it near the beginning, put it at the end or vice versa

"double" not "int"

Since this program uses real numbers, your variables should be of type "double"

You can get the address of a double $($or anything$)$ the same way we did for integers in the videos, with the & operator

A variable which has the type "pointer to double" is likewise declared as a "double $*"$

The format string to provide to scanf$()$ when reading in a double from the user is $"\%$lf$"($long float$)$ as $"\%$i$"$ only works for integers

rotate$()$ function

While it is not necessary programmatically speaking to have a separate rotate$()$ function, it is a requirement of this assignment to get further practice with using pointers.

Your rotate$()$ function should accept two "double $*"$ parameters which point to the x & y coordinates entered by the user and a simple "double" parameter which is the number of radians to rotate by

The rotate$()$ function should have a return type of void; its results $($the coordinates of the new point$)$ will simply be saved in the memory cells designated by the pointers it receives, that is$,$ when the function is done running, it will have changed the values associated with the pointers that were passed to it

Don't forget a function prototype for rotate$()$ like I always do;$$ it's function prototype should be "void rotate$($double $*,$ double $*,$ double$)"$

Using pointers

Don't forget star $(*)$ operator when working with pointers!$$ If you want to access the value the pointer points to$,$ you need $*$some$\_$ptr;$$ if you actually want the pointer itself, then leave the star off.

$..$hing$/$cyb$126\%./$rotate$\_$point$$

Please enter an x coordinate: $30$

Please enter an y coordinate: $1$

Please enter the number of degrees to rotate by: $180$

The result is $(-30\mathrm{.}000000,-1\mathrm{.}000000)$

Formulae:

Degrees to radians

$180$degrees

Rotation formulae

xnew$=$xcos$($$)-$ysin$($$)$

ynew$=$xsin$($$)+$ycos$($$)$

Notes, hints, and reminders:

Math

The library needs to be included to access the sin$()$ and cos$()$ functions as well as the M$\_$PI constant

When you compile your program with gcc$,$ don't forget to add the $"-$lm$"($link math$)$ flag to the command

If you get an error when compiling that says "undefined reference to sin$()"$ move the $"-$lm$"$ flag to a different position in the gcc command; if you had it near the beginning, put it at the end or vice versa

"double" not "int"

Since this program uses real numbers, your variables should be of type "double"

You can get the address of a double $($or anything$)$ the same way we did for integers in the videos, with the & operator

A variable which has the type "pointer to double" is likewise declared as a "double $*"$

The format string to provide to scanf$()$ when reading in a double from the user is $"\%$lf$"($long float$)$ as $"\%$i$"$ only works for integers

rotate$()$ function

While it is not necessary programmatically speaking to have a separate rotate$()$ function, it is a requirement of this assignment to get further practice with using pointers.

Your rotate$()$ function should accept two "double $*"$ parameters which point to the x & y coordinates entered by the user and a simple "double" parameter which is the number of radians to rotate by

The rotate$()$ function should have a return type of void; its results $($the coordinates of the new point$)$ will simply be saved in the memory cells designated by the pointers it receives, that is$,$ when the function is done running, it will have changed the values associated with the pointers that were passed to it

Don't forget a function prototype for rotate$()$ like I always do;$$ it's function prototype should be "void rotate$($double $*,$ double $*,$ double$)"$

Using pointers

Don't forget star $(*)$ operator when working with pointers!$$ If you want to access the value the pointer points to$,$ you need $*$some$\_$ptr;$$ if you actually want the pointer itself, then leave the star off.