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Bash bcmath functions

I have two functions for GNU bc in a Bash script.

BC_CEIL="define ceil(x) { if (x>0) { if (x%1>0) return x+(1-(x%1)) else return x } else return -1*floor(-1*x) }\n"
BC_FLOOR="define floor(x) { if (x>0) return x-(x%1) else return -1*ceil(-1*x) }\n"
echo -e "scale=2"$BC_CEIL$BC_FLOOR"ceil(2.5)" | bc

Both functions work fine in bc interactive mode. bc doesn't seem to allow multiple functions on the same line, separated; though, so I need echo -n | bc with newlines at the end of each function. The above output is 2.5 and not the expected 3.0 which I get if I type it into bc-i. It looks like Bash is calling bc for each line of echo-out, rather than echoing just one instance. Is there a workaround for this?

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2 answers


The scale must be zero for x%1

. Usually, you should only have one return from a function.

define ceil(x) { auto savescale; savescale = scale; scale = 0; if (x>0) { if (x%1>0) result = x+(1-(x%1)) else result = x } else result = -1*floor(-1*x);  scale = savescale; return result }
define floor(x) { auto savescale; savescale = scale; scale = 0; if (x>0) result = x-(x%1) else result = -1*ceil(-1*x);  scale = savescale; return result }


This scale requires a newline:

echo -e "scale=2\n"$BC_CEIL$BC_FLOOR"ceil(2.5)" | bc
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I believe it 1.

is wrong. Comparison if()

should be X >= 0

.

I believe it works



define ceil(x) {                         
    if (x >= 0) { if (x%1>0) return x+(1-(x%1)) else return x } 
    else return -1*floor(-1*x)               
}
define floor(x) {                        
    if (x >= 0) return x-(x%1)               
    else return -1*ceil(-1*x)                
}
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