Intrinsic Functions

An intrinsic function is a built-in mvBASIC function to be used on numeric operands.

Numeric Functions

In addition to the standard numeric operators (+, -, *, /), mvBASIC provides several functions for evaluating numeric calculations.

ABS	Returns the absolute value of a given expression. The absolute value of a number is its positive value, or the difference between itself and zero.
INT	Gives the integer value of an expression. It truncates the decimal portion of a number and returns the result.
REM	Takes two arguments and returns the remainder value when the first expression is divided by the second.
SQRT	Returns the square root of a positive expression.
RND	Returns a random number between 0 and the given expression minus 1.
PWR	Takes two arguments and returns the first value to the power of the second.

In addition, the following trigonometric functions are available in mvBASIC:

SIN	Returns the sine of the angle.
COS	Returns the cosine of the angle.
TAN	Returns the tangent of the angle (SIN/COS).
LN	Returns the natural logarithm (log base e) of the expression.
EXP	Returns e to the power of the expression (the inverse of LN).

The accuracy of each numeric function is dependent on the decimal precision used by the program; i.e., the number of decimal places to which numeric values are calculated. By default, all numeric values are calculated to four decimal places. To reassign this value, use the PRECISION statement. The maximum precision supported by mvBASIC is 9.

Logical Functions (NOT, NUM, ALPHA)

A logical function, or Boolean function, is one which returns either 0 or 1. A return value of 0 is taken to mean false, and a return value of 1 is taken to mean true. Logical functions are most useful in conditional statements (IF, CASE), or in the exit for loops.

In addition to the logical operators (=, <>, >, >=, <, <=, MATCH), the following intrinsic logical functions are supported in mvBASIC:

NOT	Returns the logical inverse of a given expression. That is, if the expression evaluates to 0 or the null string (" "), the NOT function returns 1; if the expression evaluates to anything other than 0 or the null string, the NOT function returns 0.
NUM	Returns 1 if the given expression is numeric, or 0 if it is nonnumeric. (Note that the NUM function might return 0 for a clearly numeric value if it contains more decimal places than the current precision.)
ALPHA	Returns 1 if the given expression is alphabetic, or 0 if it is non alphabetic.

Example

Suppose a program expects a positive number in Attribute 3 of a file item. The source code might read:

PRICE = RECORD<3>

IF NOT(NUM(PRICE)) THEN

PRINT "ERROR — NON-NUMERIC DATA IN ATTRIBUTE 3."

STOP

END ELSE

IF PRICE < 0 THEN

PRINT "ERROR — NEGATIVE DATA IN ATTRIBUTE 3."

STOP

END

Using the Boolean operators (AND, OR), the same code might read:

PRICE = RECORD<3>

IF NOT(NUM(PRICE)) OR PRICE < 0 THEN

PRINT "ERROR IN ATTRIBUTE 3 — ":

PRINT "POSITIVE NUMBER EXPECTED."

STOP

END