{"id":396,"date":"2014-02-26T15:11:50","date_gmt":"2014-02-26T15:11:50","guid":{"rendered":"http:\/\/it.tuxie.eu\/?p=396"},"modified":"2014-03-04T13:02:22","modified_gmt":"2014-03-04T13:02:22","slug":"basic-calculations-in-bash","status":"publish","type":"post","link":"http:\/\/it.tuxie.eu\/?p=396","title":{"rendered":"Basic calculations in Bash"},"content":{"rendered":"

Discussion about limits in Excel (15 decimal digits maximum) with my friend caused inspiration for writing few words about basic number magic within Bash command line.<\/p>\n

<\/p>\n

As Pi precision is one of classic benchmark, let\u00b4s try it. You can find many information about Pi number (there <\/a>and there<\/a>), anyway it\u00b4s always good to know something about bc<\/a> in *nix environment. Now we can write directly into command line something like this:<\/p>\n

ji@linux-bfq8:~> time echo \"scale=1500; 4*a(1)\" | bc -l<\/code><\/strong><\/span><\/span>
\n3.141592653589793238462643383279502884197169399375105820974944592307\\<\/span>
\n81640628620899862803482534211706798214808651328230664709384460955058\\<\/span>
\n22317253594081284811174502841027019385211055596446229489549303819644\\<\/span>
\n28810975665933446128475648233786783165271201909145648566923460348610\\<\/span>
\n45432664821339360726024914127372458700660631558817488152092096282925\\<\/span>
\n40917153643678925903600113305305488204665213841469519415116094330572\\<\/span>
\n70365759591953092186117381932611793105118548074462379962749567351885\\<\/span>
\n75272489122793818301194912983367336244065664308602139494639522473719\\<\/span>
\n07021798609437027705392171762931767523846748184676694051320005681271\\<\/span>
\n45263560827785771342757789609173637178721468440901224953430146549585\\<\/span>
\n37105079227968925892354201995611212902196086403441815981362977477130\\<\/span>
\n99605187072113499999983729780499510597317328160963185950244594553469\\<\/span>
\n08302642522308253344685035261931188171010003137838752886587533208381\\<\/span>
\n42061717766914730359825349042875546873115956286388235378759375195778\\<\/span>
\n18577805321712268066130019278766111959092164201989380952572010654858\\<\/span>
\n63278865936153381827968230301952035301852968995773622599413891249721\\<\/span>
\n77528347913151557485724245415069595082953311686172785588907509838175\\<\/span>
\n46374649393192550604009277016711390098488240128583616035637076601047\\<\/span>
\n10181942955596198946767837449448255379774726847104047534646208046684\\<\/span>
\n25906949129331367702898915210475216205696602405803815019351125338243\\<\/span>
\n00355876402474964732639141992726042699227967823547816360093417216412\\<\/span>
\n19924586315030286182974555706749838505494588586926995690927210797509\\<\/span>
\n302952<\/span><\/p>\n

real\u00a0\u00a0 \u00a00m1.045s<\/span>
\nuser\u00a0\u00a0 \u00a00m1.032s<\/span>
\nsys\u00a0\u00a0 \u00a00m0.000s<\/span>
\nji@linux-bfq8:~> <\/span><\/p>\n

Pi number with 1500 decimal places – not bad, right? \ud83d\ude42 -l<\/strong><\/span> at the end is hinting bc to use standard math library (as function arctan – a() is part of it). Ok, some basics first (without any comments, I think all will be very simple):<\/p>\n

ji@linux-bfq8:~> echo 10\/3<\/strong><\/span><\/span>
\n 10\/3<\/span>
\n ji@linux-bfq8:~> echo 10\/3 | bc -l<\/strong><\/span><\/span>
\n 3.33333333333333333333<\/span>
\n ji@linux-bfq8:~> echo \"scale=5;10\/3\" | bc -l<\/code><\/strong><\/span><\/span>
\n 3.33333<\/span>
\n ji@linux-bfq8:~> echo \"obase=16; 255\" | bc<\/code><\/strong><\/span><\/span>
\n FF<\/span>
\n ji@linux-bfq8:~> echo \"obase=2; 255\" | bc<\/code><\/strong><\/span><\/span>
\n 11111111<\/span><\/p>\n

With all documentation + scripting abilities + your imagination you can handle very complex math problems with Bash. If you want to get higher, try awk or\/and perl. Do you feel the infinity?……<\/p>\n

-a-<\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

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