Mathematical Functions -> 32 This function is safe to use with  BIGINT  values. Returns the arc cosine of  X , that is, the value whose cosine is  X . Returns  NULL  if  X  is not in the range  -1 to  1 . Returns the arc sine of  X , that is, the value whose sine is  X . Returns  NULL  if  X  is not in the range  -1  to  1 . Returns the arc tangent of the two variables  X  and  Y . It is similar to calculating the arc tangent of  Y  /  X , except that the signs of both arguments are used to determine the quadrant of the result. CEIL()  is a synonym for  CEILING() . Returns the smallest integer value not less than  X . 2142 • CEILING( X ) • CEIL( X ) • ATAN( Y , X ) ,  ATAN2( Y , X ) Returns the arc tangent of  X , that is, the value whose tangent is  X . • ATAN( X ) • ASIN( X ) • ACOS( X ) mysql>  SELECT ACOS(1); -> 0 mysql>  SELECT ACOS(1.0001); -> NULL mysql>  SELECT ACOS(0); -> 1.5707963267949 mysql>  SELECT ASIN(0.2); -> 0.20135792079033 mysql>  SELECT ASIN(’foo’); +-------------+ | ASIN(’foo’) | +-------------+ | 0 | +-------------+ 1 row in set, 1 warning (0.00 sec) mysql>  SHOW WARNINGS; +---------+------+-----------------------------------------+ | Level | Code | Message | +---------+------+-----------------------------------------+ | Warning | 1292 | Truncated incorrect DOUBLE value: ’foo’ | +---------+------+-----------------------------------------+ mysql>  SELECT ATAN(2); -> 1.1071487177941 mysql>  SELECT ATAN(-2); -> -1.1071487177941 mysql>  SELECT ATAN(-2,2); -> -0.78539816339745 mysql>  SELECT ATAN2(PI(),0); -> 1.5707963267949