Option menu   Numbers and Precision

This option designates the number manipulation on the program unit where no OPTION ARITHMETIC is written.

Decimal

A numeric value that a numeric variable holds is a decimal floating point number.
Precision of a variable is 13 digits but 15 digits for Windows 32bit , linux(x86), linux(X86_64) or Intel Mac .
When More Places Displayed option is selected, computational results are displayed without modification.

Binary approximately 16 digits

Numrical variables are 64 bit.
The computational results are displayed rounded to decimal of 15 digits.
Displayed numeric and calculation result of transcendental functions or MAT statements may not be correct on the environment where 80 bit extended floating point opearion is not available such as in Windows 64bit or ARM.

Complex

Complex numbers are represented internally by a couple of binary double precision numbers.
PRINT statements displays an imaginary number by putting the two numbers in parentheses.
When the base is a positive number, exponents can be imaginary numbers on a power operation.
When the base is an imaginary number, only exponents of integers between -2147483647 and 2147483647 are allowed.
The domain of the functions ABS(x), SQR(x), EXP(x) and LOG(x) are extended to the complex numbers.
The functions COMPLEX(x,y)，RE(x)，IM(x)，CONJ(x)，ARG(x) are provided exclusively on the complex operation mode.
Transform functions SCALE and SHIFT are extended to the complex numbers.
If an imaginary number is used anywhere else, an exception may be caused.

Refer to
OPTION ARITHMETIC
Complex Numbers
Rational Numbers