Octave

Tips on GNU Octave

• Get some books
• It's inefficient on the CPU, so use it for fun and prototyping.

argv

# NOTE: numbers passed into argv are treated as (ascii) char
# must convert with str2num, or some other
e.g. (call script with ./script 20
#!/usr/bin/octave

arg_list = argv();
HOWLONG=arg_list{1}

# NOTE: numbers passed into argv are treated as (ascii) char
# which means 0 is around 40 in binary.
# must convert with str2num, or some other
# cast() will not fix this (as it casts the binary)

display("How long is: ")
class(HOWLONG) 
news2 = str2num(HOWLONG)
display("news2 is now: ")
class(news2)

if loop

#don't forget quotes on numbers here
#if  HOWLONG == "1"
#       SQLQUERYNUM = 288;
#elseif HOWLONG == "3"
#       SQLQUERYNUM = 288 * 3;
#elseif HOWLONG == "7"
#       SQLQUERYNUM =  288 * 7;
#elseif HOWLONG == "14"
#       SQLQUERYNUM = 288 * 14;
#else
#display("incorrect time to search")
#display("Try, 1, 3, 7, 14")
#exit();
#en

sprintf

1. basic sprintf (req's quotes)
2. val1="test"
3. val2="something"
4. sprintf("%s%s",val1,val2)
5. if you want to assign to variable, sprintf(variable,"%s%s",val1,val2)
6. won't work, but ofc
7. newvar = sprintf("%s%s",val1,val2)
8. will

call function with parenthesis or not

1. dynamically generate print filename at runtime
2. https://www.mathworks.com/matlabcentral/answers/148-how-do-i-dynamically-generate-a-file-name-for-save-in-matlab
3. essentially, if you myvar = sprintf(something...)
4. you have to print(myvar)
5. not print myvar
6. so parenthesis are required (but they are not always required for e.g. print)

invert Y axis

1. display(p(:,2)) (all times)
2. display(p(:,1)) (all values)
3. vals = p(:,1)
4. EDIT: the below was a bug.
5. it appears you can't invert the (p(:,1)) in plot, with either common commands used to invert Y axis.
6. these cmds are: axis(ij) after plot, as well as set(gca,'YDir','reverse');, and plot (flipud(p(:, 2)), p(:, 1)) (this latter one inverts only the X axis, not Y
7. so instead, send it to a new variable
8. flipud(vals)
9. EDIT: this isn't what I want to do. it flips the array upside down. instead, I want the high end
10. of the y axis to be at the bottom, and the low numbers to be at the top.
11. https://savannah.gnu.org/bugs/?47223
12. I dug into the bug tracker, and also dl'd source code. looks like i have an old version
13. installing debian 10 resolved this (could also have used backports in stretch).

Database Package with Devuan 9

Devuan ascii has octave 4.0. ascii backports has 4.4, but not octave-struct (without breaking in devuan). Must migrate to Devuan Beowulf to get full octave 4.4.