Contrived and a touch pretentious
|
| Author | Content |
|---|---|
| richo123 Apr 06, 2007 5:50 PM EDT |
Instead of using a fancy shell tool like bc why not just write a regular c or fortran program? It doesn't take long to both write and compile and you have the program for future reference. Easy and no need to remember yet more convoluted shell syntax. |
| jezuch Apr 07, 2007 1:39 AM EDT |
What if you want to calculate something in a shell script? echo 'int main() { /* whatever */ }' >> /tmp/calculatesomething.c gcc /tmp/calculatesomething.c result=$(/tmp/calculatesomething) I'd say it's contrived ;) |
| DarrenR114 Apr 07, 2007 7:38 AM EDT |
create a simple 'eval.pl' script:
#!/usr/bin/perl
# make sure that the above path to perl is correct
use strict;
my $expr = shift;
my $result = eval($expr);
print $expr . "=" . $result . "\n"; make eval.pl executable: $> chmod +x eval.pl run the script: $>./eval.pl 1+1 result: 1+1=2 To get an approximation of pi: $> ./eval.pl 22/7 It's not as accurate the actual pi, but then you can do './eval.pl 22/7*\(3^2\)' to find a reasonable approximation of the area of a cirle with a radius of '3'. |
| richo123 Apr 07, 2007 8:22 AM EDT |
Darren: How about program pi double precision xpi xpi=4.*atan(1.0) print *,'pi=',xpi end Accurate to 8 places. Edit: Dammit it is only accurate to 6 places |
| DarrenR114 Apr 07, 2007 9:44 AM EDT |
@richo123 using my PERL script, as is, with your technique, instead of 22/7, to find pi, I would use: $> ./eval.pl \(atan2\(1,5\)*4-atan2\(1,239\)\)*4 (from a BASH command line.) To find the area of a circle with radius 3 then: $> ./eval.pl \(atan2\(1,5\)*4-atan2\(1,239\)\)*4*3**2 giving this result: (atan2(1,5)*4-atan2(1,239))*4*3**2=28.2743338823081 |
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