Syntax: mdefine [name [expression [: [type] [emin emax]]]
where 'name' = the name of the model. If "name" is a previously defined model with mdefine, the current definition will overwrite the old one, and the user is warned; if it is a built-in model, however, the user will be asked to use a different name.
'expression' = a string of arithmetic expression. Simple rules for expression:
1) The energy term, must be 'e' or 'E' in the expression. Other words, which are not numerical constants nor internal functions, are assumed to be model parameters.
2) If a convolution model varies with the location on the spectrum to be convolved, the special variable ".e" or ".E" may be used to refer to the convolution point.
3) The expression may contain spaces for better readability.
'type' = user may optionally specify the type of the model, the valid types are (add, mul, con). (Mix models are not yet implemented as of v12.5.0) Please note that the character ":" must be used to separate the options from the "expression". If "type" is not given default is add.
'emin emax' = user may also specify the minimum and maximum energy values for the model, the default values are 1.e-20 and 1.e+20, respectively.
Note that MDEFINE can also be used to display and delete previously defined models:
1) To display the name, type and expression of all previously defined models:
2) To display the name, type and expression of a previously defined model by the name, MNAME:
XSPEC12> mdefine MNAME
3) To delete a previously defined model by the name, MNAME:
XSPEC12> mdefine MNAME :
The following operators are recognized in an expression:
+ = plus operator
- = minus operator
* = multiplying operator
/ = dividing operator
** = exponentiation operator
^ = exponentiation operator
The following internal functions are supported:
Unary Functions .............................
EXP (expr) = exp of a vector expression
SIN (expr) = sine of vector expression in rad
SIND (expr) = sine of a vector expression in degree
COS (expr) = cosine of a vector expression in rad
COSD (expr) = cosine of a vector expression in degree
TAN (expr) = tangent of a vector expression in rad
TAND (expr) = tangent of a vector expression in degree
LOG (expr) = base 10 log of a vector expression
LN (expr) = natural log of a vector expression
SQRT (expr) = sqrt of a vector expression
ABS (expr) = absolute value of a vector expression
INT (expr) = integer part of a vector expression
ASIN (expr) = sin^-1 of a vector expression in rad
ACOS (expr) = cos^-1 of a vector expression in rad
MEAN (expr) = mean value of a vector expression
DIM (expr) = dimension of a vector expression
SMIN (expr) = minimum value of a vector expression
SMAX (expr) = maximum value of a vector expression
Binary Functions ............................
MAX (expr1, expr2) = maximum of the two vector expressions
MIN (expr1, expr2) = minimum of the two vector expressions
XSPEC12> mdef dplaw E**p1 + f*E**p2 ! define a model named "dplaw" with 3 parameters, p1, p2, f
XSPEC12> mdef junk a*e+b*log(e)/sin(e) ! define a model named "junk" with 2 parameters (a, b)
XSPEC12> mdef junk2 exp(-a*e) : mul ! define a model named "junk2" with 1 parameter, a; the option following ":" says that it will be a multiplicative model.
XSPEC12> mdef junk3 0.2+B*e : mul ! define a model named "junk3" with 1 parameter, B, options following ":" says that this will be a multiplicative model
XSPEC12> mdef bb E**2/T**4/(exp(E/T)-1) ! try to define a blackbody model with name "bb", you get warning:
***Warning: bb is a pre-defined model
Please use a different name for your model.
XSPEC12> mdef sg exp(-E^2/(2*A*.E)) / sqrt(6.283*A*sqrt(.E)) : con
! this defines a Gaussian convolution model with sigma varying with square root of energy.
XSPEC12> mdef junk2 : ! delete junk2
XSPEC12> mdef ! display all user-defined models
-- Name ---- Type ------ Expression -----