Go to the first, previous, next, last section, table of contents.
Floating Point
Definitions for Floating Point
- Function: BFFAC (exp,n)
- BFLOAT version of the Factorial (shifted Gamma) function. The 2nd argument is how many digits to retain and return, it's a good idea to request a couple of extra. This function is available by doing LOAD(BFFAC); .
- Function: BFLOAT (X)
- converts all numbers and functions of numbers to bigfloat numbers. Setting FPPREC[16] to N, sets the bigfloat precision to N digits. If FLOAT2BF[FALSE] is FALSE a warning message is printed when a floating point number is converted into a bigfloat number (since this may lead to loss of precision).
- Function: BFPSI (n,z,fpprec)
- gives polygammas of real arg and integer order. For digamma, BFPSI0(z,fpprec) is more direct. Note -BFPSI0(1,fpprec) provides BFLOATed %GAMMA. To use this do LOAD(BFFAC);
- Variable: BFTORAT
-
default: [FALSE] controls the conversion of bfloats to
rational numbers. If
BFTORAT:FALSE
RATEPSILON will be used to control the conversion (this results in relatively small rational numbers). If
BFTORAT:TRUE
, the rational number generated will accurately represent the bfloat.
- Variable: BFTRUNC
- default: [TRUE] causes trailing zeroes in non-zero bigfloat numbers not to be displayed. Thus, if BFTRUNC:FALSE, BFLOAT(1); displays as 1.000000000000000B0. Otherwise, this is displayed as 1.0B0.
- Function: CBFAC (z,fpprec)
- a factorial for complex bfloats. It may be used by doing LOAD(BFAC); For more details see share2/bfac.usg.
- Function: FLOAT (exp)
- converts integers, rational numbers and bigfloats in exp to floating point numbers. It is also an EVFLAG, FLOAT causes non-integral rational numbers and bigfloat numbers to be converted to floating point.
- Variable: FLOAT2BF
- default: [FALSE] if FALSE, a warning message is printed when a floating point number is converted into a bigfloat number (since this may lead to loss of precision).
- Function: FLOATDEFUNK
-
- is a utility for making floating point functions from
mathematical expression. It will take the input expression and FLOAT it,
then OPTIMIZE it, and then insert MODE_DECLAREations for all the variables.
This is THE way to use ROMBERG, PLOT2, INTERPOLATE, etc. e.g.
EXP:some-hairy-macsyma-expression;
FLOATDEFUNK('F,['X],EXP);will define the function F(X) for you. (Do PRINTFILE(MCOMPI,DOC,MAXDOC); for more details.)
- Variable: FPPREC
- default: [16] - Floating Point PRECision. Can be set to an integer representing the desired precision.
- Variable: FPPRINTPREC
- default: [0] - The number of digits to print when printing a bigfloat number, making it possible to compute with a large number of digits of precision, but have the answer printed out with a smaller number of digits. If FPPRINTPREC is 0 (the default), or >= FPPREC, then the value of FPPREC controls the number of digits used for printing. However, if FPPRINTPREC has a value between 2 and FPPREC-1, then it controls the number of digits used. (The minimal number of digits used is 2, one to the left of the point and one to the right. The value 1 for FPPRINTPREC is illegal.)
- Function: ?ROUND (x,&optional-divisor)
-
round the floating point X to the nearest integer. The argument
must be a regular system float, not a bigfloat. The ? beginning the name
indicates this is normal common lisp function.
(C3) ?round(-2.8); (D3) - 3
- Function: ?TRUNCATE (x,&optional-divisor)
- truncate the floating point X towards 0, to become an integer. The argument must be a regular system float, not a bigfloat. The ? beginning the name indicates this is normal common lisp function.
(C4) ?truncate(-2.8); (D4) - 2 (C5) ?truncate(2.4); (D5) 2 (C6) ?truncate(2.8); (D6) 2
- Variable: ZUNDERFLOW
- default: [TRUE] - if FALSE, an error will be signaled if floating point underflow occurs. Currently in NIL Macsyma, all floating-point underflow, floating-point overflow, and division-by-zero errors signal errors, and this switch is ignored.
Go to the first, previous, next, last section, table of contents.