A fixed point basic calculator for DASH. Post: 303025604

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Operating Systems OS X (Apple) A fixed point basic calculator for DASH. Post 303025604 by wisecracker on Tuesday 6th of November 2018 05:07:37 PM

11-06-2018

Registered User

Quote:

Originally Posted by Corona688

Here's a quick bash-only version for positive numbers. The trick is reading the values in. Once you do that the rest is straightforward.

Code:

DP=3
MOD=1000

function readnum {
        IFS="." read N FRAC <<<"$1"
        [ "$N" = "0" ] && N=""
        for((X=0; X<DP; X++))
        do
                D="${FRAC:$X:1}"
                [ -z "$D" ] && D="0"
                N="$N$D" # Prepend digits to N
        done
}

readnum "0.5"

echo "Integer $N is fixed point $((N/MOD)).$((N%MOD))"

I can see what you are doing, but forgive my ignorance; apart from the obvious bashisms, how do I use 'read' to input values directly from command line arguments without disk thrashing in POSIX 'dash'?
Everything MUST centre around 'dash' or POSIX 'sh'.
As for 'zsh', I can't be responsible for a non POSIX compliant shell.
This is the whole point of this [futile] exercise to see what is possible and what better than Fixed Point Arithmetic.
And I already assume a "fractional" part of 1000000000 and use "%.9f" to add any zeros to the end.
Anyhow I will try out your "MINUS" modification tomorrow.
Multiplication and division are harder still in 'dash'.

Back tomorrow.
HTH.

Bazza.

wisecracker

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LEARN ABOUT MOJAVE

tk_getdash

Tk_GetDash(3)						       Tk Library Procedures						     Tk_GetDash(3)

__________________________________________________________________________________________________________________________________________________

NAME

       Tk_GetDash - convert from string to valid dash structure.

SYNOPSIS

       #include <tk.h>

       int
       Tk_GetDash(interp, string, dashPtr)

ARGUMENTS

       Tcl_Interp *interp (in)	      Interpreter to use for error reporting.

       const char * string (in)       Textual value to be converted.

       Tk_Dash *dashPtr (out)	      Points to place to store the dash pattern value converted from string.
_________________________________________________________________

DESCRIPTION

       These  procedure  parses  the  string and fills in the result in the Tk_Dash structure. The string can be a list of integers or a character
       string containing only ".,-_" or spaces. If all goes well, TCL_OK is returned. If string does not have the proper syntax then TCL_ERROR	is
       returned, an error message is left in the interpreter's result, and nothing is stored at *dashPtr.

       The  first possible syntax is a list of integers. Each element represents the number of pixels of a line segment. Only the odd segments are
       drawn using the "outline" color. The other segments are drawn transparent.

       The second possible syntax is a character list containing only 5 possible characters ".,-_ ".  The space can be used to enlarge	the  space
       between other line elements, and can not occur as the first position in the string. Some examples:
		  -dash .     = -dash {2 4}
		  -dash -     = -dash {6 4}
		  -dash -.    = -dash {6 4 2 4}
		  -dash -..   = -dash {6 4 2 4 2 4}
		  -dash {. }  = -dash {2 8}
		  -dash ,     = -dash {4 4}

       The  main  difference  of this syntax with the previous is that it is shape-conserving. This means that all values in the dash list will be
       multiplied by the line width before display. This assures that "."  will always be displayed as a dot and "-" always as a  dash	regardless
       of the line width.

       On  systems where only a limited set of dash patterns, the dash pattern will be displayed as the most close dash pattern that is available.
       For example, on Windows only the first 4 of the above examples are available. The last 2 examples will  be  displayed  identically  as  the
       first one.

KEYWORDS

       dash, conversion

Tk									8.3							     Tk_GetDash(3)