The Korn shell's let command performs arithmetic. ksh88 is restricted to integer arithmetic. ksh93 can do floating-point arithmetic as well. The Korn shell provides a way to substitute arithmetic values (for use as command arguments or in variables); base conversion is also possible:
$(( expr ))  | Use the value of the enclosed arithmetic expression.  | 
B#n  | Interpret integer n in numeric base B. For example, 8#100 specifies the octal equivalent of decimal 64.  | 
The Korn shell uses arithmetic operators from the C programming language; in decreasing order of precedence.
ksh93 provides access to the standard set of mathematical functions. They are called using C function call syntax.
| Name | Function | Name | Function | 
|---|---|---|---|
| abs | Absolute value  | log | Natural logarithm  | 
| acos | Arc cosine  | sin | Sine  | 
| asin | Arc sine  | sinh | Hyperbolic sine  | 
| cos | Cosine  | sqrt | Square root  | 
| cosh | Hyperbolic cosine  | tan | Tangent  | 
| exp | Exponential function  | tanh | Hyperbolic tangent  | 
| int | Integer part of floating-point number  | 
See the let command for more information and examples:
let "count=0" "i = i + 1" Assign i and count let "num % 2" Test for an even number (( percent >= 0 && percent <= 100 )) Test the range of a value
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