The Expression Feature In TrueGrid®

An expression in TrueGrid® is defined to be any FORTRAN like expressions enclosed in square brackets. these expressions can be used any place a number is required in the input stream. For example;

scale [sqrt(2.1)/17.2]

This can be combined with parameters so that expressions become dependent on values defined in the PARAMETER command. For example;

PARAMETER a 2.1 b 17.2;

scale [sqrt(%a)/%b]

Properties Of Expressions

(*) Integer, floating point, and exponential numbers and parameters can be used as operands and arguments to functions.

(*) All calculations are done in floating point.

(*) Unitary and binary arithmetic operators + and -.

(*) Binary arithmetic operators *, /, **, and ^.

(*) Parentheses to specify order of operations where the default order is given to:

First - exponentiation ( ** or ^ ),

Second - multiplication ( * ) and division ( / ),

Third - addition ( + ) and subtraction ( - ).

(*) The expression can be continued to the next line by using a space and the ampersand ( & ) at the end of the line.

(*) All illegal operations cause warnings.

(*) All trigonometric operations are in degrees.

Expressions Can Call Functions

(*) INT(x): truncates x to an integer

(*) NINT(x): rounds x to the nearest integer

(*) ABS(x): absolute value of x

(*) MOD(a,b): a modulo b

(*) SIGN(a,b): transfer the sign of b to a

(*) MAX(x1,x2,...,xn): maximum value of a list of numbers

(*) MIN(x1,x2,...,xn): minimum value of a list of numbers

(*) SQRT(x): square root of x where x most be positive

(*) EXP(x): exponential of x where x must not exceed 85.19

(*) LOG(x): natural logarithm where x must be positive

(*) LOG10(x): common logarithm base 10 where x must be positive

(*) SIN(x): trigonometric sine of x

(*) COS(x): trigonometric cosine of x

(*) TAN(x): trigonometric tangent of x where abs(x) can not be 90

(*) ASIN(x): trigonometric arcsine of x where abs(x) can not exceed 1

(*) ACOS(x): trigonometric arccosine of x where abs(x) can not exceed 1

(*) ATAN(x): trigonometric arctangent

(*) ATAN2(y,x): trigonometric arctangent with two arguments

(*) SINH(x): hyperbolic sine

(*) COSH(x): hyperbolic cosine

(*) RAND(seed,mean): uniform random number from 0 to 1

(*) NORM(seed,mean,sig): normal random number

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