Expressions are constructed from operands and operators. The operators of an expression indicate which operations to apply to the operands. The order of evaluation of operators in an expression is determined by the precedence and associativity of the operators.
Numerical values
A numeric value can be an integer (e.g. 12, 44), a floating point number (3.14159), an integer or floating point number followed by an integer exponent (1e14, 2.65e3), or an integer or floating point number followed by one of the following scale factors:
Suffix  Scale  Description 

f, F  10^{15}  femto 
p, P  10^{12}  pico 
n, N  10^{9}  nano 
u, U, µ  10^{6}  micro 
MIL  25.4*10^{6}  mil 
m, M  10^{3}  milli 
k, K  10^{3}  kilo 
MEG  10^{6}  mega 
g, G  10^{9}  giga 
t, T  10^{12}  tera 
Characters that follow a number and do not represent a scale suffix and characters that follow a scale suffix are ignored. So the numbers: 1000, 1000.0, 1000Hz, 1e3, 1.0e3, 1KHz, and 1K all represent the same value.
Warning: 

All suffixes can be entered either in lower case or upper case. Use MEG to indicate 10^{6}. The suffix m or M is always interpreted as milli (10^{3}). Scale suffixes must be entered immediately after the number, spaces between the number and scale suffixes are not allowed. 
Boolean values
Relational operators, equality and boolean operators consider the value zero as false and any nonzero value as true.
Arithmetic operators
Operator  Description  Type  Example 

  Unary minus  Unary  x 
+  Addition  Binary  y+x 
  Subtraction  Binary  yx 
*  Multiplication  Binary  y*x 
/  Division  Binary  y/x 
\ DIV 
Integer division  Binary  y\x 
% MOD 
Modulus (remainder after integer division)  Binary  y%x 
^  Exponentiation. x^{y}. The same function as the POW(x, y).  Binary  x^y 
**  Exponentiation. x^{y}. The same function as the PWR(x, y). This operator is defined only for compatibility with the models developed for PSPICE. Do not use in expressions relating to generators of type B.  Binary  x**y 
Relational operators
These operators produce a result equal to 0.0 if the relation is false and 1.0 if the relation is true.
Operator  Description  Type 

<  Define a "less than" relational operator that returns 1.0 if the first operand is less than the second, 0.0 otherwise  Binary 
>  Define a "greater than" relational operator that returns 1.0 if the first operand is greater than the second, 0.0 otherwise  Binary 
<=  Define a "less than or equal" relational operator that returns 1.0 if the first operand is less than or equal to the second, 0.0 otherwise  Binary 
>=  Define a "greater than or equal" relational operator that returns 1.0 if the first operand is greater than or equal to the second, 0.0 otherwise  Binary 
Equality operators
These operators produce a result equal to 0.0 if the relation is false and 1.0 if the relation is true.
Operator  Description  Type 

==  The equality operator returns 1.0 if the values of its operands are equal, 0.0 otherwise  Binary 
!= <> 
The inequality operator returns 0.0 if its operands are equal, 1.0 otherwise  Binary 
Boolean operators
These operators produce a result equal to 0.0 (FALSE) or 1.0 (TRUE). The value of the operands is:
FALSE if operand is zero
TRUE if operand is not zero
Operator  Description  Type 

&& AND 
Computes the boolean AND of its operands; that is, the result is true (1.0) if and only if both its operands are true.  Binary 
NAND  Computes the boolean NAND of its operands; that is, the result is false (0.0) if and only if both its operands are true.  Binary 
 OR 
Computes the boolean OR of its operands; that is, the result is false (0.0) if and only if both its operands are false.  Binary 
NOR  Computes the boolean NOR of its operands; that is, the result is true (1.0) if and only if both its operands are false.  Binary 
XOR  Computes the boolean XOR of its operands; that is,
the result is true (1.0) if and only if inputs differ (one is true, the
other is false). 
Binary 
! NOT 
Boolean negation operator is a unary operator that negates its operand. It returns true (1.0) if and only if its operand is false.  Unary 
Logical operators
These operators produce a result equal to LZERO (FALSE) or LONE (TRUE). The value of the operands is:
LONE if operand >= VTHRESH
LZERO if operand < VTHRESH
The parameters VTHRESH, LONE and LZERO are set in Simulator options.
Operator  Description  Type 

&  Computes the logical AND of its operands; that is, the result is true (LONE) if and only if both its operands are true (LONE)  Binary 
  Computes the logical OR of its operands; that is, the result is false (LZERO) if and only if both its operands are false (LZERO)  Binary 
~  Logical negation operator is a unary operator that negates its operand. It returns true (LONE) if and only if its operand is false (LZERO)  Unary 
Constants
Name  Description  Value 

BOLTZ  Boltzman constant  1.38062^{23} 
C  The speed of light  2.997925^{8} 
E  The constant base of the natural logarithm  2.718... 
FALSE  False  0.0 
ECHARGE  The charge of an electron  1.60219^{19} 
KELVIN  Absolute zero in °C  273.15 
LN10  The natural logarithm of 10  2.302... 
LN2  The natural logarithm of 2  0.693... 
LOG10E  The base10 logarithm of e  0.434... 
LOG2E  The base2 logarithm of e  1.442... 
PI  The constant pi  3.141... 
PLANCK  Planck's constant  6.62620^{34} 
SQRT2  The square root of 2  1.414... 
TRUE  True  1.0 
TWOPI  The constant pi * 2  6.282... 
Variables
Name  Description 

TIME  The current time in transient analysis. 
TEMP  Current temperature. 
GMIN  The lowest permissible conductance, can be set using the option GMIN. 
FREQ  The current AC frequency in radians. 
VT  Thermal voltage (k•T/q = 1.38E23•T/1.602E19) 
Functions
If the argument of log(), ln(), or sqrt() becomes less than zero, the absolute value of the argument is used. If a divisor becomes zero or the argument of log() or ln() becomes zero, an error will result. Other problems may occur when the argument for a function in a partial derivative enters a region where that function is undefined.
Function  Description 

ABS(x)  Absolute value of x 
ACOS(x)  Inverse cosine of x 
ACOSH(x)  Inverse hyperbolic cosine of x 
ASIN(x)  Inverse sine of x 
ASINH(x)  Inverse hyperbolic sine of x 
ATAN(x) ARCTAN(x) 
Inverse tangent of x 
ATANH(x)  Inverse hyperbolic tangent of x 
ATAN2(x,y)  Arctan of x/y 
CEIL(x)  Return the smallest integer that is greater than or equal to x 
COS(x)  Cosine of x 
COSH(x)  Hyperbolic cosine of x 
DEG(x)  Converts the value of x from radians to degrees 
EXP(x)  Exponential e^{x} 
FLOOR(x)  Return the largest integer that is less than or equal to x 
IF(x,a,b)  If x is different from zero returns a, otherwise returns b. The discontinuity created by the two branches of the operator IF can cause convergence problems 
LIMIT(x,min,max)  Returns min if x<min, returns max if x>max, otherwise returns x 
LN(x)  Return the natural logarithm of x. If the argument becomes less than zero, the absolute value of the argument is used. If the argument becomes zero, an error will result. 
LOG(x)  If is included in an expression of an element of type B then calculates the decimal logarithm. If is included in an expression of an element of type E or G then calculates the natural logarithm. If the argument becomes less than zero, the absolute value of the argument is used. If the argument becomes zero, an error will result. 
LOG10(x)  Return the decimal logarithm of x. If the argument becomes less than zero, the absolute value of the argument is used. If the argument becomes zero, an error will result. 
MAX(a,b)  Maximum of a and b 
MIN(a,b)  Minimum of a and b 
POW(x,y)  x^{y}. Same as x^y. 
PWR(x,y)  x^{y} 
PWRS(x,y)  If x > 0 return x^{y}. If x < 0 return x^{y} 
RAD(x)  Converts the value of x from degrees to radians 
ROUND(x)  Return the nearest integer to x 
SGN(x)  If x < 0 return 1. If x > 0 return 1. If x = 0 return 0 
SIN(x)  Sine of x 
SINH(x)  Hyperbolic sine of x 
SQRT(x)  Return the square root of x. If the argument becomes less than zero, the absolute value of the argument is used. 
STP(x)  If x < 0 return 0, 1 otherwise 
TABLE(x,x1,y1,x2,y2...xn,yn)  Return the y value corresponding to x. The value of y is calculated by linear interpolation between the pairs of values xn, yn of the table. If x is greater than the max xn, then the value is the yn associated with the largest xn. If x is less than the smallest xn, then the value is the yn associated with the smallest xn. 
TAN(x)  Tangent of x 
TANH(x)  Hyperbolic tangent of x 
U(x)  If x < 0 return 0, 1 otherwise 
URAMP(x)  If x < 0 return 0, x otherwise 
Note: 

The argument of the trigonometric functions are in radians.

BitaBit Functions
The following functions convert their arguments in 32bit integers.
Function  Description 

BITNOT(x)  Binary NOT. 
BITAND(x,y)  Binary AND. 
BITOR(x,y)  Binary OR. 
BITXOR(x,y)  Binary XOR. 
BITODD(x)  The output is 1 when an odd number of bits is 1. 
BITEVEN(x)  The output is 1 when an even number of bits is 1. 
BITSHL(x,n,w,m)  Shift left of w bits of the number x repeated n times. m is reload mode: 0=0, 1=1, 2=keeps the bit, 3=keeps and inverts the bit, 4=rotates the opposite bit, 5=rotates and inverts the opposite bit. 
BITSHR(x,n,w,m)  Shift right of w bits of the number x repeated n times. m is reload mode: 0=0, 1=1, 2=keeps the bit, 3=keeps and inverts the bit, 4=rotates the opposite bit, 5=rotates and inverts the opposite bit. 
Examples
B1 0 1 I=cos(v(1))+sin(v(2))
B1 0 1 V=ln(cos(log(v(1,2)^2)))v(3)^4+v(2)^v(1)
B1 3 4 I=17
B1 3 4 V=exp(pi^i(vdd))