COMPUTE
Basic form
COMPUTE n = arithexp.
Effect
Evaluates the arithmetic expression arithexp and
places the result in the field n .
Allows use of the four basic calculation types + ,  ,
* and / , the whole number division operators DIV
(quotient) and MOD (remainder), the exponentiation operator
** (exponentiation " X ** Y means X to the power of
Y ) as well as the functions listed below.
When evaluating mixed expressions, functions have priority. Then comes
exponentiation, followoed by the "point operations" * , / ,
DIV and MOD , and finally + and  . Any
combination of parentheses is also allowed.
The fields involved are usually of type I , F or P ,
but there are exceptions to this rule (see below).
You can omit the key word COMPUTE .
Builtin functions

Functions for all number types
ABS Amount (absolute value) x of x
SIGN Sign (preceding sign) of x;

1 x > 0

SIGN( x ) = 0 if x = 0

1 x < 0
CEIL Smallest whole number value not less than x
FLOOR Greatest whole number value not greater than x
TRUNC Whole number part of x
FRAC Decimal part of x
ACOS Arc cosine(x) in the range [pi/2, pi/2], x from [1, 1]
ASIN Arc cosine(x) in the range [0, pi], x aus [1, 1]
ATAN Arc tangent(x) in the range [pi/2, pi/2] (pi =
3.1415926535897932)
COS Cosine of an angle specified in the arc
SIN Sine of an angle specified in the arc
TAN Tangent of an angle specified in the arc
COSH Hyperbola cosine
SINH Hyperbola sine
TANH Hyperbola tangent
EXP Exponential function for base e = 2.7182818284590452
LOG Natural logarithm (i.e. base e) of a positive number
LOG10 Logarithm of x for base 10, x > 0
SQRT Square root of a nonnegative number
STRLEN Length of a string up to the last nonblank character
(i.e. the occupied length )
Function expressions consist of three parts:
Function identifier directly followed by an opening parenthesis
Argument
Closing parenthesis
All parts of an expression, particularly any parts of a function
expression, must be separated from each other by at least one blank.
Example
The following statements, especially the arithmetic
expressions, are syntactically correct:

DATA: I1 TYPE I, I2 TYPE I, I3 TYPE I,
F1 TYPE F, F2 TYPE F,
WORD1(10), WORD2(20).
...
F1 = ( I1 + EXP( F2 ) ) * I2 / SIN( 3  I3 ).
COMPUTE F1 = SQRT( SQRT( ( I1 + I2 ) * I3 ) + F2 ).
I1 = STRLEN( WORD1 ) + STRLEN( WORD2 ).
Notes
When used in calculations, the amount of CPU time needed
depends on the data type. In very simple terms, type I is the
cheapest, type F needs longer and type P is the most
expensive.
Normally, packed numbers arithmetic is used to evaluate arithmetic
expressions. If, however, the expression contains a floating point
function, or there is at least one type F operand, or the result
field is type F , floating point arithmetic is used instead for
the entire expression. On the other hand, if only type I fields
or date and time fields occur (see below), the calculation involves
integer operations.
You can also perform calculations on numeric fields other than type
I , F or P . Before executing calculations, the
necessary type conversions are performed (see
MOVE ). You can, for instance, subtract
one date field (type D ) from another, in order to calculate the
number of days difference. However, for reasons of efficiency, only
operands of the same number type should be used in one arithmetic
expression (apart from the operands of STRLEN ). This means that
no conversion is necessary and special optimization procedures can be
performed.
Division by 0 results in termination unless the dividend is also 0
( 0 / 0 ). In this case, the result is 0.
As a string processing command, the STRLEN operator treats
operands (regardless of type) as character strings, without triggering
internal conversions. On the other hand, the operands of floating point
functions are converted to type F if they have another type.
Example
Date and time arithmetic

DATA: DAYS TYPE I,
DATE_FROM TYPE D VALUE '19911224',
DATE_TO TYPE D VALUE '19920101',
DAYS = DATE_TO  DATE_FROM.
DAYS now contains the value 8.

DATA: SECONDS TYPE I,
TIME_FROM TYPE T VALUE '200000',
TIME_TO TYPE T VALUE '020000'.
SECONDS = ( TIME_TO  TIME_FROM ) MOD 86400.
SECONDS now contains the value 21600 (i.e. 6 hours). The
operation " MOD 86400 " ensures that the result is always a
positive number, even if the period extends beyond midnight.
Note
Packed numbers arithmetic:
All P fields are treated as whole numbers. Calculations
involving decimal places require additional programming to include
multiplication or division by 10, 100, ... . The DECIMALS
specification with the DATA declaration is effective only for output
with WRITE .
If, however, fixed point arithmetic is active, the
DECIMALS specification is also taken into account. In this case,
intermediate results are calculated with maximum accuracy (31 decimal
places). This applies particularly to division.
For this reason, you should always set the program attribute "Fixed
point arithmetic".
Example

DATA P TYPE P.
P = 1 / 3 * 3.
Without "fixed point arithmetic", P has the value 0, since
" 1 / 3 " is rounded down to 0.
With fixed point arithmetic, P has the value 1, since the
intermediate result of " 1 / 3 " is
0.333333333333333333333333333333.
Note
Floating point arithmetic
With floating point arithmetic, you must always expect some loss of
accuracy through rounding errors (ABAP/4
number types ).
Note
Exponentiation
The exponential expression "x**y" means x*x*...*x y times, provided
that y is a natural number. For any value of y, x**y is explained by
exp(y*log(x)).
Operators of the same ranke are evaluated from left to right. Only the
exponential operator, as is usual in mathematics, is evaluated from
right to left . The expression " 4 ** 3 ** 2 " thus corresponds
to " 4 ** ( 3 ** 2 ) " and not " ( 4 ** 3 ) ** 2 ", so the
result is 262144 and not 4096.
The following resrtictions apply for the expression " X ** Y ": If
X is equal to 0, Y must be positive. If X is
negative, Y must be a whole number.
Note
DIV and MOD
The whole number division operators DIV and MOD are
defined as follows:
so that:
n1 = ndiv * n2 + nmod
ndiv is a whole number
0 <= nmod < n2
A runtime error occurs if n2 is equal to 0 and n1 is not equal to 0.
Example

DATA: D1 TYPE I, D2 TYPE I, D3 TYPE I, D4 TYPE I,
M1 TYPE P DECIMALS 1, M2 TYPE P DECIMALS 1,
M3 TYPE P DECIMALS 1, M4 TYPE P DECIMALS 1,
PF1 TYPE F VALUE '+7.3',
PF2 TYPE F VALUE '+2.4',
NF1 TYPE F VALUE '7.3',
NF2 TYPE F VALUE '2.4',
D1 = PF1 DIV PF2. M1 = PF1 MOD PF2.
D2 = NF1 DIV PF2. M2 = NF1 MOD PF2.
D3 = PF1 DIV NF2. M3 = PF1 MOD NF2.
D4 = NF1 DIV NF2. M4 = NF1 MOD NF2.
The variables now have the following values:
D1 = 3, M1 = 0.1,
D2 =  4, M2 = 2.3,
D3 =  3, M3 = 0.1,
D4 = 4, M4 = 2.3.
Example
Functions ABS , SIGN , CEIL ,
FLOOR , TRUNC , FRAC

DATA: I TYPE I,
P TYPE P DECIMALS 2,
M TYPE F VALUE '3.5',
D TYPE P DECIMALS 1.
P = ABS( M ). " 3,5
I = P. " 4  commercially rounded
I = M. " 4
I = CEIL( P ). " 4  next largest whole number
I = CEIL( M ). " 3
I = FLOOR( P ). " 3  next smallest whole number
I = FLOOR( M ). " 4
I = TRUNC( P ). " 3  whole number part
I = TRUNC( M ). " 3
D = FRAC( P ). " 0,5  decimal part
D = FRAC( M ). " 0,5
Notes
Floating point functions
Although the functions SIN , COS and TAN are
defined for any numbers, the results are imprecise if the argument is
greater than about 1E8 , i.e. 10**8.
The logarithm for a base other than e or 10 is calculated as follows:
Logarithm of b for base a = LOG( b ) / LOG( a )
Note
Runtime errors
Depending on the operands, the above operators and functions can cause
runtime errors (e.g. when evaluating the
logarithm with a negative argument).
Related
ADD ,
SUBTRACT ,
MULTIPLY ,
DIVIDE ,
MOVE
Index
© SAP AG 1996