float8-small-is-zero_1.out

PostgreSQL 8.1.4的源码 适用于Linux下的开源数据库系统

--
-- FLOAT8
--
CREATE TABLE FLOAT8_TBL(f1 float8);
INSERT INTO FLOAT8_TBL(f1) VALUES ('    0.0   ');
INSERT INTO FLOAT8_TBL(f1) VALUES ('1004.30  ');
INSERT INTO FLOAT8_TBL(f1) VALUES ('   -34.84');
INSERT INTO FLOAT8_TBL(f1) VALUES ('1.2345678901234e+200');
INSERT INTO FLOAT8_TBL(f1) VALUES ('1.2345678901234e-200');
-- test for underflow and overflow handling
SELECT '10e400'::float8;
ERROR:  "10e400" is out of range for type double precision
SELECT '-10e400'::float8;
ERROR:  "-10e400" is out of range for type double precision
SELECT '10e-400'::float8;
 float8 
--------
     0
(1 row)

SELECT '-10e-400'::float8;
 float8 
--------
     0
(1 row)

-- bad input
INSERT INTO FLOAT8_TBL(f1) VALUES ('');
ERROR:  invalid input syntax for type double precision: ""
INSERT INTO FLOAT8_TBL(f1) VALUES ('     ');
ERROR:  invalid input syntax for type double precision: "     "
INSERT INTO FLOAT8_TBL(f1) VALUES ('xyz');
ERROR:  invalid input syntax for type double precision: "xyz"
INSERT INTO FLOAT8_TBL(f1) VALUES ('5.0.0');
ERROR:  invalid input syntax for type double precision: "5.0.0"
INSERT INTO FLOAT8_TBL(f1) VALUES ('5 . 0');
ERROR:  invalid input syntax for type double precision: "5 . 0"
INSERT INTO FLOAT8_TBL(f1) VALUES ('5.   0');
ERROR:  invalid input syntax for type double precision: "5.   0"
INSERT INTO FLOAT8_TBL(f1) VALUES ('    - 3');
ERROR:  invalid input syntax for type double precision: "    - 3"
INSERT INTO FLOAT8_TBL(f1) VALUES ('123           5');
ERROR:  invalid input syntax for type double precision: "123           5"
-- special inputs
SELECT 'NaN'::float8;
 float8 
--------
    NaN
(1 row)

SELECT 'nan'::float8;
 float8 
--------
    NaN
(1 row)

SELECT '   NAN  '::float8;
 float8 
--------
    NaN
(1 row)

SELECT 'infinity'::float8;
  float8  
----------
 Infinity
(1 row)

SELECT '          -INFINiTY   '::float8;
  float8   
-----------
 -Infinity
(1 row)

-- bad special inputs
SELECT 'N A N'::float8;
ERROR:  invalid input syntax for type double precision: "N A N"
SELECT 'NaN x'::float8;
ERROR:  invalid input syntax for type double precision: "NaN x"
SELECT ' INFINITY    x'::float8;
ERROR:  invalid input syntax for type double precision: " INFINITY    x"
SELECT 'Infinity'::float8 + 100.0;
ERROR:  type "double precision" value out of range: overflow
SELECT 'Infinity'::float8 / 'Infinity'::float8;
 ?column? 
----------
      NaN
(1 row)

SELECT 'nan'::float8 / 'nan'::float8;
 ?column? 
----------
      NaN
(1 row)

SELECT '' AS five, * FROM FLOAT8_TBL;
 five |          f1          
------+----------------------
      |                    0
      |               1004.3
      |               -34.84
      | 1.2345678901234e+200
      | 1.2345678901234e-200
(5 rows)

SELECT '' AS four, f.* FROM FLOAT8_TBL f WHERE f.f1 <> '1004.3';
 four |          f1          
------+----------------------
      |                    0
      |               -34.84
      | 1.2345678901234e+200
      | 1.2345678901234e-200
(4 rows)

SELECT '' AS one, f.* FROM FLOAT8_TBL f WHERE f.f1 = '1004.3';
 one |   f1   
-----+--------
     | 1004.3
(1 row)

SELECT '' AS three, f.* FROM FLOAT8_TBL f WHERE '1004.3' > f.f1;
 three |          f1          
-------+----------------------
       |                    0
       |               -34.84
       | 1.2345678901234e-200
(3 rows)

SELECT '' AS three, f.* FROM FLOAT8_TBL f WHERE  f.f1 < '1004.3';
 three |          f1          
-------+----------------------
       |                    0
       |               -34.84
       | 1.2345678901234e-200
(3 rows)

SELECT '' AS four, f.* FROM FLOAT8_TBL f WHERE '1004.3' >= f.f1;
 four |          f1          
------+----------------------
      |                    0
      |               1004.3
      |               -34.84
      | 1.2345678901234e-200
(4 rows)

SELECT '' AS four, f.* FROM FLOAT8_TBL f WHERE  f.f1 <= '1004.3';
 four |          f1          
------+----------------------
      |                    0
      |               1004.3
      |               -34.84
      | 1.2345678901234e-200
(4 rows)

SELECT '' AS three, f.f1, f.f1 * '-10' AS x 
   FROM FLOAT8_TBL f
   WHERE f.f1 > '0.0';
 three |          f1          |           x           
-------+----------------------+-----------------------
       |               1004.3 |                -10043
       | 1.2345678901234e+200 | -1.2345678901234e+201
       | 1.2345678901234e-200 | -1.2345678901234e-199
(3 rows)

SELECT '' AS three, f.f1, f.f1 + '-10' AS x
   FROM FLOAT8_TBL f
   WHERE f.f1 > '0.0';
 three |          f1          |          x           
-------+----------------------+----------------------
       |               1004.3 |                994.3
       | 1.2345678901234e+200 | 1.2345678901234e+200
       | 1.2345678901234e-200 |                  -10
(3 rows)

SELECT '' AS three, f.f1, f.f1 / '-10' AS x
   FROM FLOAT8_TBL f
   WHERE f.f1 > '0.0';
 three |          f1          |           x           
-------+----------------------+-----------------------
       |               1004.3 |               -100.43
       | 1.2345678901234e+200 | -1.2345678901234e+199
       | 1.2345678901234e-200 | -1.2345678901234e-201
(3 rows)

SELECT '' AS three, f.f1, f.f1 - '-10' AS x
   FROM FLOAT8_TBL f
   WHERE f.f1 > '0.0';
 three |          f1          |          x           
-------+----------------------+----------------------
       |               1004.3 |               1014.3
       | 1.2345678901234e+200 | 1.2345678901234e+200
       | 1.2345678901234e-200 |                   10
(3 rows)

SELECT '' AS one, f.f1 ^ '2.0' AS square_f1
   FROM FLOAT8_TBL f where f.f1 = '1004.3';
 one | square_f1  
-----+------------
     | 1008618.49
(1 row)

-- absolute value 
SELECT '' AS five, f.f1, @f.f1 AS abs_f1 
   FROM FLOAT8_TBL f;
 five |          f1          |        abs_f1        
------+----------------------+----------------------
      |                    0 |                    0
      |               1004.3 |               1004.3
      |               -34.84 |                34.84
      | 1.2345678901234e+200 | 1.2345678901234e+200
      | 1.2345678901234e-200 | 1.2345678901234e-200
(5 rows)

-- truncate 
SELECT '' AS five, f.f1, trunc(f.f1) AS trunc_f1
   FROM FLOAT8_TBL f;
 five |          f1          |       trunc_f1       
------+----------------------+----------------------
      |                    0 |                    0
      |               1004.3 |                 1004
      |               -34.84 |                  -34
      | 1.2345678901234e+200 | 1.2345678901234e+200
      | 1.2345678901234e-200 |                    0
(5 rows)

-- round 
SELECT '' AS five, f.f1, round(f.f1) AS round_f1
   FROM FLOAT8_TBL f;
 five |          f1          |       round_f1       
------+----------------------+----------------------
      |                    0 |                    0
      |               1004.3 |                 1004
      |               -34.84 |                  -35
      | 1.2345678901234e+200 | 1.2345678901234e+200
      | 1.2345678901234e-200 |                    0
(5 rows)

-- ceil / ceiling
select ceil(f1) as ceil_f1 from float8_tbl f;
       ceil_f1        
----------------------
                    0
                 1005
                  -34
 1.2345678901234e+200
                    1
(5 rows)

select ceiling(f1) as ceiling_f1 from float8_tbl f;
      ceiling_f1      
----------------------
                    0
                 1005
                  -34
 1.2345678901234e+200
                    1
(5 rows)

-- floor
select floor(f1) as floor_f1 from float8_tbl f;
       floor_f1       
----------------------
                    0
                 1004
                  -35
 1.2345678901234e+200
                    0
(5 rows)

-- sign
select sign(f1) as sign_f1 from float8_tbl f;
 sign_f1 
---------
       0
       1
      -1
       1
       1
(5 rows)

-- square root 
SELECT sqrt(float8 '64') AS eight;
 eight 
-------
     8
(1 row)

SELECT |/ float8 '64' AS eight;
 eight 
-------
     8
(1 row)

SELECT '' AS three, f.f1, |/f.f1 AS sqrt_f1
   FROM FLOAT8_TBL f
   WHERE f.f1 > '0.0';
 three |          f1          |        sqrt_f1        
-------+----------------------+-----------------------
       |               1004.3 |      31.6906926399535
       | 1.2345678901234e+200 | 1.11111110611109e+100
       | 1.2345678901234e-200 | 1.11111110611109e-100
(3 rows)

-- power
SELECT power(float8 '144', float8 '0.5');
 power 
-------
    12
(1 row)

-- take exp of ln(f.f1) 
SELECT '' AS three, f.f1, exp(ln(f.f1)) AS exp_ln_f1
   FROM FLOAT8_TBL f
   WHERE f.f1 > '0.0';
 three |          f1          |       exp_ln_f1       
-------+----------------------+-----------------------
       |               1004.3 |                1004.3
       | 1.2345678901234e+200 | 1.23456789012338e+200
       | 1.2345678901234e-200 | 1.23456789012339e-200
(3 rows)

-- cube root 
SELECT ||/ float8 '27' AS three;
 three 
-------
     3
(1 row)

SELECT '' AS five, f.f1, ||/f.f1 AS cbrt_f1 FROM FLOAT8_TBL f;
 five |          f1          |       cbrt_f1        
------+----------------------+----------------------
      |                    0 |                    0
      |               1004.3 |      10.014312837827
      |               -34.84 |    -3.26607421344208
      | 1.2345678901234e+200 | 4.97933859234765e+66
      | 1.2345678901234e-200 |  2.3112042409018e-67
(5 rows)

SELECT '' AS five, * FROM FLOAT8_TBL;
 five |          f1          
------+----------------------
      |                    0
      |               1004.3
      |               -34.84
      | 1.2345678901234e+200
      | 1.2345678901234e-200
(5 rows)

UPDATE FLOAT8_TBL
   SET f1 = FLOAT8_TBL.f1 * '-1'
   WHERE FLOAT8_TBL.f1 > '0.0';
SELECT '' AS bad, f.f1 * '1e200' from FLOAT8_TBL f;
ERROR:  type "double precision" value out of range: overflow
SELECT '' AS bad, f.f1 ^ '1e200' from FLOAT8_TBL f;
ERROR:  result is out of range
SELECT '' AS bad, ln(f.f1) from FLOAT8_TBL f where f.f1 = '0.0' ;
ERROR:  cannot take logarithm of zero
SELECT '' AS bad, ln(f.f1) from FLOAT8_TBL f where f.f1 < '0.0' ;
ERROR:  cannot take logarithm of a negative number
SELECT '' AS bad, exp(f.f1) from FLOAT8_TBL f;
ERROR:  result is out of range
SELECT '' AS bad, f.f1 / '0.0' from FLOAT8_TBL f;
ERROR:  division by zero
SELECT '' AS five, * FROM FLOAT8_TBL;
 five |          f1           
------+-----------------------
      |                     0
      |                -34.84
      |               -1004.3
      | -1.2345678901234e+200
      | -1.2345678901234e-200
(5 rows)

-- test for over- and underflow 
INSERT INTO FLOAT8_TBL(f1) VALUES ('10e400');
ERROR:  "10e400" is out of range for type double precision
INSERT INTO FLOAT8_TBL(f1) VALUES ('-10e400');
ERROR:  "-10e400" is out of range for type double precision
INSERT INTO FLOAT8_TBL(f1) VALUES ('10e-400');
INSERT INTO FLOAT8_TBL(f1) VALUES ('-10e-400');
-- maintain external table consistency across platforms
-- delete all values and reinsert well-behaved ones
DELETE FROM FLOAT8_TBL;
INSERT INTO FLOAT8_TBL(f1) VALUES ('0.0');
INSERT INTO FLOAT8_TBL(f1) VALUES ('-34.84');
INSERT INTO FLOAT8_TBL(f1) VALUES ('-1004.30');
INSERT INTO FLOAT8_TBL(f1) VALUES ('-1.2345678901234e+200');
INSERT INTO FLOAT8_TBL(f1) VALUES ('-1.2345678901234e-200');
SELECT '' AS five, * FROM FLOAT8_TBL;
 five |          f1           
------+-----------------------
      |                     0
      |                -34.84
      |               -1004.3
      | -1.2345678901234e+200
      | -1.2345678901234e-200
(5 rows)