Home
Main website
Display Sidebar
Hide Ads
Recent Changes
View Source:
dc(1)
Edit
PageHistory
Diff
Info
LikePages
DC !!!DC NAME SYNOPSIS DESCRIPTION OPTIONS Printing Commands Arithmetic Stack Control Registers Parameters Strings Status Inquiry Miscellaneous BUGS ---- !!NAME dc - an arbitrary precision calculator !!SYNOPSIS dc [[-V] [[--version] [[-h] [[--help] [[-e scriptexpression] [[--expression=scriptexpression] [[-f scriptfile] [[--file=scriptfile] [[file ...] !!DESCRIPTION ''Dc'' is a reverse-polish desk calculator which supports unlimited precision arithmetic. It also allows you to define and call macros. Normally ''dc'' reads from the standard input; if any command arguments are given to it, they are filenames, and ''dc'' reads and executes the contents of the files before reading from standard input. All normal output is to standard output; all error output is to standard error. A reverse-polish calculator stores numbers on a stack. Entering a number pushes it on the stack. Arithmetic operations pop arguments off the stack and push the results. To enter a number in ''dc'', type the digits with an optional decimal point. Exponential notation is not supported. To enter a negative number, begin the number with ``_''. ``-'' cannot be used for this, as it is a binary operator for subtraction instead. To enter two numbers in succession, separate them with spaces or newlines. These have no meaning as commands. !!OPTIONS ''Dc'' may be invoked with the following command-line options: __-V__ __--version__ Print out the version of ''dc'' that is being run and a copyright notice, then exit. __-h__ __--help__ Print a usage message briefly summarizing these command-line options and the bug-reporting address, then exit. __-e__ ''script'' __--expression=__''script'' Add the commands in ''script'' to the set of commands to be run while processing the input. __-f__ ''script-file'' __--file=__''script-file'' Add the commands contained in the file ''script-file'' to the set of commands to be run while processing the input. If any command-line parameters remain after processing the above, these parameters are interpreted as the names of input files to be processed. A file name of __-__ refers to the standard input stream. The standard input will processed if no file names are specified. !!Printing Commands __p__ Prints the value on the top of the stack, without altering the stack. A newline is printed after the value. __n__ Prints the value on the top of the stack, popping it off, and does not print a newline after. __P__ Pops off the value on top of the stack. If it it a string, it is simply printed without a trailing newline. Otherwise it is a number, and the integer portion of its absolute value is printed out as a KSK 0k1/ [[_1*]sx d0 could also accomplish this function, except for the side-effect of clobbering the x register. __f__ Prints the entire contents of the stack without altering anything. This is a good command to use if you are lost or want to figure out what the effect of some command has been. !!Arithmetic __+__ Pops two values off the stack, adds them, and pushes the result. The precision of the result is determined only by the values of the arguments, and is enough to be exact. __-__ Pops two values, subtracts the first one popped from the second one popped, and pushes the result. __*__ Pops two values, multiplies them, and pushes the result. The number of fraction digits in the result depends on the current precision value and the number of fraction digits in the two arguments. __/__ Pops two values, divides the second one popped from the first one popped, and pushes the result. The number of fraction digits is specified by the precision value. __%__ Pops two values, computes the remainder of the division that the __/__ command would do, and pushes that. The value computed is the same as that computed by the sequence __Sd dld/ Ld*-__ . __~__ Pops two values, divides the second one popped from the first one popped. The quotient is pushed first, and the remainder is pushed next. The number of fraction digits used in the division is specified by the precision value. (The sequence __!SdSn lnld/ !LnLd%__ could also accomplish this function, with slightly different error checking.) __^__ Pops two values and exponentiates, using the first value popped as the exponent and the second popped as the base. The fraction part of the exponent is ignored. The precision value specifies the number of fraction digits in the result. __|__ Pops three values and computes a modular exponentiation. The first value popped is used as the reduction modulus; this value must be a non-zero number, and should be an integer. The second popped is used as the exponent; this value must be a non-negative number, and any fractional part of this exponent will be ignored. The third value popped is the base which gets exponentiated, which should be an integer. For small integers this is like the sequence __Sm^Lm%__, but, unlike __^__, this command will work with arbitrarily large exponents. __v__ Pops one value, computes its square root, and pushes that. The precision value specifies the number of fraction digits in the result. Most arithmetic operations are affected by the ``precision value'', which you can set with the __k__ command. The default precision value is zero, which means that all arithmetic except for addition and subtraction produces integer results. !!Stack Control __c__ Clears the stack, rendering it empty. __d__ Duplicates the value on the top of the stack, pushing another copy of it. Thus, ``4d*p'' computes 4 squared and prints it. __r__ Reverses the order of (swaps) the top two values on the stack. !!Registers ''Dc'' provides at least 256 memory registers, each named by a single character. You can store a number or a string in a register and retrieve it later. __s__''r'' Pop the value off the top of the stack and store it into register ''r''. __l__''r'' Copy the value in register ''r'' and push it onto the stack. This does not alter the contents of ''r''. Each register also contains its own stack. The current register value is the top of the register's stack. __S__''r'' Pop the value off the top of the (main) stack and push it onto the stack of register ''r''. The previous value of the register becomes inaccessible. __L__''r'' Pop the value off the top of register ''r'''s stack and push it onto the main stack. The previous value in register ''r'''s stack, if any, is now accessible via the __l__''r'' command. !!Parameters ''Dc'' has three parameters that control its operation: the precision, the input radix, and the output radix. The precision specifies the number of fraction digits to keep in the result of most arithmetic operations. The input radix controls the interpretation of numbers typed in; all numbers typed in use this radix. The output radix is used for printing numbers. The input and output radices are separate parameters; you can make them unequal, which can be useful or confusing. The input radix must be between 2 and 16 inclusive. The output radix must be at least 2. The precision must be zero or greater. The precision is always measured in decimal digits, regardless of the current input or output radix. __i__ Pops the value off the top of the stack and uses it to set the input radix. __o__ Pops the value off the top of the stack and uses it to set the output radix. __k__ Pops the value off the top of the stack and uses it to set the precision. __I__ Pushes the current input radix on the stack. __O__ Pushes the current output radix on the stack. __K__ Pushes the current precision on the stack. !!Strings ''Dc'' can operate on strings as well as on numbers. The only things you can do with strings are print them and execute them as macros (which means that the contents of the string are processed as ''dc'' commands). All registers and the stack can hold strings, and ''dc'' always knows whether any given object is a string or a number. Some commands such as arithmetic operations demand numbers as arguments and print errors if given strings. Other commands can accept either a number or a string; for example, the __p__ command can accept either and prints the object according to its type. __[[__''characters''__]__ Makes a string containing ''characters'' (contained between balanced __[[__ and __]__ characters), and pushes it on the stack. For example, __[[foo]P__ prints the characters __foo__ (with no newline). __a__ The top-of-stack is popped. If it was a number, then the low-order byte of this number is converted into a string and pushed onto the stack. Otherwise the top-of-stack was a string, and the first character of that string is pushed back. __x__ Pops a value off the stack and executes it as a macro. Normally it should be a string; if it is a number, it is simply pushed back onto the stack. For example, __[[1p]x__ executes the macro __1p__ which pushes __1__ on the stack and prints __1__ on a separate line. Macros are most often stored in registers; __[[1p]sa__ stores a macro to print __1__ into register __a__, and __lax__ invokes this macro. ____''r'' Pops two values off the stack and compares them assuming they are numbers, executing the contents of register ''r'' as a macro if the original top-of-stack is greater. Thus, __1 2__ will invoke register __a__'s contents and __2 1__ will not. __!__''r'' Similar but invokes the macro if the original top-of-stack is not greater than (less than or equal to) what was the second-to-top. ____''r'' Similar but invokes the macro if the original top-of-stack is less. __!__''r'' Similar but invokes the macro if the original top-of-stack is not less than (greater than or equal to) what was the second-to-top. __=__''r'' Similar but invokes the macro if the two numbers popped are equal. __!=__''r'' Similar but invokes the macro if the two numbers popped are not equal. __?__ Reads a line from the terminal and executes it. This command allows a macro to request input from the user. __q__ exits from a macro and also from the macro which invoked it. If called from the top level, or from a macro which was called directly from the top level, the __q__ command will cause ''dc'' to exit. __Q__ Pops a value off the stack and uses it as a count of levels of macro execution to be exited. Thus, __3Q__ exits three levels. The __Q__ command will never cause ''dc'' to exit. !!Status Inquiry __Z__ Pops a value off the stack, calculates the number of digits it has (or number of characters, if it is a string) and pushes that number. __X__ Pops a value off the stack, calculates the number of fraction digits it has, and pushes that number. For a string, the value pushed is 0. __z__ Pushes the current stack depth: the number of objects on the stack before the execution of the __z__ command. !!Miscellaneous __!__ Will run the rest of the line as a system command. Note that parsing of the ! __#__ Will interpret the rest of the line as a comment. __:__''r'' Will pop the top two values off of the stack. The old second-to-top value will be stored in the array ''r'', indexed by the old top-of-stack value. __;__''r'' Pops the top-of-stack and uses it as an index into the array ''r''. The selected value is then pushed onto the stack. Note that each stacked instance of a register has its own array associated with it. Thus __1 0:a 0Sa 2 0:a La 0;ap__ will print 1, because the 2 was stored in an instance of 0:a that was later popped. !!BUGS Email bug reports to __bug-dc@gnu.org__. ----
4 pages link to
dc(1)
:
Man1d
bc(1)
gcalc(1)
TwoLetterCommands
This page is a man page (or other imported legacy content). We are unable to automatically determine the license status of this page.
