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Top Forums Shell Programming and Scripting Simple Scientific calculator for ADE, the UNIX environment for the AMIGA A1200(HD). Post 303037057 by wisecracker on Monday 22nd of July 2019 12:33:42 PM
Old 07-22-2019
A very practical use of scicalc and this will be the last upload...
I am creating an audio function generator and wanted to use ASCII only for all of the waveforms so that a simple arbitrary waveform could be created using a text editor, and all other waveforms can be edited too.
Well this is not fast but generates a sinewave in pure ASCII only. It is a practical use of 'scicalc'.
Code:
#!/bin/sh

# #!/usr/local/bin/dash
# text_sinewaves.sh

WAVEFORM=""

# 64 bytes per cycle:
# for ANGLE in $( seq 0.0 5.625 359.0 )
# 8 bytes per cycle:
for ANGLE in $( seq 0.0 45.0 359.0 )
do
    FLOAT=$( ~/Desktop/Code/Shell/scicalc "(((sin((${ANGLE}*pi)/180)+1)/2.0)*94)+32" )
    # Don't use awk's """int()""" function as it rounds down only, use """printf "%.0f" ...""" instead.
    WAVEFORM=${WAVEFORM}$( printf \\$( printf "%03o" $( printf "%.0f" "${FLOAT}" ) ) )
done
echo "${WAVEFORM}"
echo "Length = ${#WAVEFORM} bytes."

Results; editing for both for loops:
Code:
Last login: Mon Jul 22 16:18:46 on ttys000
AMIGA:amiga~> cd Desktop/Code/Shell
AMIGA:amiga~/Desktop/Code/Shell> ./text_sinewaves.sh
OTX]aeimpsvxz|}~~~}|zxvspmiea]XTOJFA=951.+(&$"!   !"$&(+.159=AFJ
Length = 64 bytes.
AMIGA:amiga~/Desktop/Code/Shell> ./text_sinewaves.sh
Op~pO. .
Length = 8 bytes.
AMIGA:amiga~/Desktop/Code/Shell> _

How does it work:
First things first, there are 95 normal printable ASCII characters from ASCII 32 decimal " ", and ASCII 126 decimal "~".
The _centreline_ character is ASCII 79 decimal "O", (not ZERO but capital O).
So we have three conditions to take care of, the minimum value must be no less than ASCII 32 " ", the centreline pseudo-DC ASCII 79 "O", (Direct Current level), and finally the maximum value must be no more ASCII 126 "~".

Now consider the expression "(((sin((${ANGLE}*pi)/180)+1)/2.0)*94)+32" ...
There is no need for any start and end parentheses as this is catered for inside 'scicalc'; it does not matter if you add them though.
As 'sin(x)' from 0 to 360 degrees goes from 0 to +1 to 0 to -1 and finally back to 0 again we have to remove the negative part so +1 is added to every calculated result.
This now moves the values to 1 to 2 to 1 to 0 and finally back to 1 again.
When that is done those values are divided by 2 to give the range 0.5 to 1 to 0.5 to 0 and finally back to 0.5.
0.5 is now the centreline, or DC, and this is now multiplied by the (number_of_printable_characters - 1).
We are not done yet; as this will go from 0.0 to 94.0 then the whole has to be shifted up so 0.0 becomes 32.0 and 94.0 becomes 126.0 so 32 must be finally added, and voila, using the script 8 or 64 byte ASCII single cycle pseudo-sinewave is created.
I hope this is lucid enough.
Note that 'printf "%.0f" ' is used to create the integer values, see the code...
(And also doing this manually would take ages.)
Enjoy...

Bazza.

Last edited by wisecracker; 07-22-2019 at 01:49 PM.. Reason: Code tags, adding spaces.
 

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ctype(3C)																 ctype(3C)

NAME
ctype: isalnum(), isalpha(), isascii(), isblank(), iscntrl(), isdigit(), isgraph(), islower(), isprint(), ispunct(), isspace(), isupper(), isxdigit() - classify characters according to type SYNOPSIS
DESCRIPTION
These functions classify character-coded integer values according to the rules of the coded character set identified by the last successful call to (see setlocale(3C)). Each function is a predicate returning nonzero for true, zero for false. If has not been called successfully, characters are classified according to the rules of the default ASCII 7-bit coded character set (see setlocale(3C)). is defined on all integer values; the other functions are defined for the range (EOF) through RETURN VALUE
The functions return nonzero under the following circumstances; zero otherwise: c is an alphanumeric (letters or digits). c is a letter. c is any ASCII character code between 0 and 0177, inclusive. c is a blank character; that is, a space or a tab. c is a control character (in ASCII: character codes less than 040 and the delete character(0177)). c is a decimal digit (in ASCII: characters [0-9]). c is a visible character (in ASCII: printing characters, excluding the space character(040)). c is a lowercase letter. c is a printing character. c is a punctuation character (in ASCII: any printing character except the space character(040), digits, letters). c is a character that creates whitespace in displayed text (in ASCII: space, tab, carriage return, newline, verti- cal tab, and formfeed). c is an uppercase letter. c is a hexadecimal digit (in ASCII: characters [0-9], [A-F] or [a-f]). If the argument to any of these functions is outside the domain of the function, the result is undefined. EXTERNAL INFLUENCES
Environment Variables The category determines the classification of character type. International Code Set Support Single-byte character code sets are supported. WARNINGS
These functions are supplied both as library functions and as macros defined in the header. Normally, the macro versions are used. To obtain the library function, either use a to remove the macro definition or, if compiling in ANSI-C mode, enclose the function name in parenthesis or take its address. The following example uses the library functions for and AUTHOR
was developed by IBM, OSF, and HP. SEE ALSO
setlocale(3C), ascii(5), thread_safety(5). STANDARDS CONFORMANCE
ctype(3C)
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