user45252: 
Arduino: 1.8.5 (Windows 8.1), Board: "Arduino/Genuino Uno"

C:\Users\julie_000\Documents\Arduino\BIO_199\BIO_199.ino: In function 'void loop()':

BIO_199:19: error: too few arguments to function 'long int map(long int, long int, long int, long int, long int)'

   t1 = map(2, 0, 1023, 2);

                         ^

In file included from sketch\BIO_199.ino.cpp:1:0:

C:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino/Arduino.h:253:6: note: declared here

 long map(long, long, long, long, long);

      ^

exit status 1
too few arguments to function 'long int map(long int, long int, long int, long int, long int)'

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.
How do I fix this error?

user4143: map takes 5 parameters, not 4.  You have the original lower and upper bounds, the desired lower and upper bounds, but you forgot the actual value you want to map:
map(value, fromLow, fromHigh, toLow, toHigh)

So
t1 = map(t2, 2, 0, 1023, 2);

(assuming those numbers are actually meaningful...)

45252: <p><a href="https://i.stack.imgur.com/woLd3.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/woLd3.png" alt="enter image description here"></a></p>

<pre><code>Arduino: 1.8.5 (Windows 8.1), Board: "Arduino/Genuino Uno"

C:\Users\julie_000\Documents\Arduino\BIO_199\BIO_199.ino: In function 'void loop()':

BIO_199:19: error: too few arguments to function 'long int map(long int, long int, long int, long int, long int)'

   t1 = map(2, 0, 1023, 2);

                         ^

In file included from sketch\BIO_199.ino.cpp:1:0:

C:\Program Files (x86)\Arduino\hardware\arduino\avr\cores\arduino/Arduino.h:253:6: note: declared here

 long map(long, long, long, long, long);

      ^

exit status 1
too few arguments to function 'long int map(long int, long int, long int, long int, long int)'
</code></pre>

<p>This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.</p>

<p>How do I fix this error?</p>
 4143: <p><code>map</code> takes 5 parameters, not 4.  You have the original lower and upper bounds, the desired lower and upper bounds, but you forgot the actual value you want to map:</p>

<pre><code>map(value, fromLow, fromHigh, toLow, toHigh)
</code></pre>

<p>So</p>

<pre><code>t1 = map(t2, 2, 0, 1023, 2);
</code></pre>

<p>(assuming those numbers are actually meaningful...)</p>
