Three years ago, I posted a short post about Matlab’s built-in Easter egg in the * spy* function. Apparently, when running

*with no input arguments, it uses an undocumented default built-in sparse matrix that generates the white spy in the famous Spy vs. Spy comics series:*

**spy**>> spy;

As was recently reported by AurÃ©lien, the default built-in sparse matrix has changed in R2011a (not R2011b as in the original report):

If you ask me, the previous (white spy) image had more relevance to the * spy* function… I assume the new image was not chosen arbitrarily – if anyone has some insight as to why this image was chosen and its relevance to

*, please post a comment.*

**spy**** Addendum**: The original spy image can still be generated using the following code snippet:

c = [';@3EA4:aei7]ced.CFHE;4\T>*Y>,dL0,HOQQMJLJE9PX[[Q.ZF.\JTCA1dd'

'<A;FB:;bfj8^df//DGIF<5]UF+ZH-eM>-IorRPNMPIE-Y\\R8[I8]SUDW2e+'

'=4BGC;<cgk9_e00DEOJG=6^VG,[I.fN?5jpsSQPNQPF.Z,]S9`S9cTWVX:+,'

':5CHD<=4hlh`f11EFPKHA7&WH-\J/gOC?kqtTRRORQJ8--^TB+T=dWYWY;,_'

';6D3E=>7imiag2IFOQLID8''XI.]K0"PD@l32UZhP//P988_WC,U>+Z^Y\<2`'

'<82BF>?8jnjbhLJGPRMJE9/YJ/`L1#QMC$;;V[iv09QE99,XD.YB,[_\]=3a'

'>9;CG?@9kokc2MKHQSOKF:0ZL0aM2$RNG%AAW\jw9E.FEE-_G8aG.d`]_W5+'

'?:CDH@A:lpld3NLIRTPLG=1[M1bN3%SOH4BBX]kx:J9LLL8`H9bJ/+d_dX6,'

'@;DEIAB;mqmePOMJSUQMJ>2\N2cO4&TPP@HCY^lyDKEMMN9+I@+S8,+deY7^'

'8@EFJBC<4rnfQPNPTVRNKB3]O3dP5''UQQCIDZ_mzEPFNNOE,RA,T9/,++\8_'

'9A2G3CD=544gRQPQUWUOLE4^P4"Q6(VRRIJE[`n{KQKOOPK-SE.W:F/,,]Z+'

':BDH4DE>655hSRQRVXVPMF5_Q5#R>)eSSJKF\ao0L.L-WUL.VF8XCH001_[,'

';3EI<EO?766iTSRSWYWQNG6$R6''S?*fTTlLQ]bp1M/P.XVP8[H9]DIDA=`\]'

'?4D3=FP@877jUTSTXZXROK7%S7(TF+gUUmMR^cq:N9Q8YZQ9_I>cIJEB>d_^'

'@5E@>GQA98b3VUTUY*YSPL8&T>)UI,hVhnNS_dr;PE.9Z[RCaR?+JTFC?e`+'

'79FA?HRB:9c4WVUVZ+ZWQM=,WG*VJ-"gi4OT`es<QL9E[\TD+SA,SWUVW+d,'

'8:3B@JSX;:dVXWVW[,[XRN>-XH+bK.#hj@PUvftDRMEF,]UH,UB.TYVWX,e\'

'9;ECAKTY<;eWYXWX\:)YSOE.YI,cL/$ikCqV1guE/PFL-^XI-YG/WZWXY1+]'

':AFDBLUZ=<fXZYXY,;*ZTPF/ZJ-dM0%j#Jrt2hxH0QKM8,YJ.ZI8[^YY\2,,'

';B3ECMV[>jgY[ZYZ-<7[XQG0[K.eN1&"$K2u:iyO9.PN9-_K8aJ9\_]\]82['

'?CEFDNW\?khZ\[Z[==8\YRH1\M/!O2''#%m31Bw0PE/QXE8+R9bS;da^]_93\'

'@2FGEOX]ali[]\[\>>9(ZSL2]N0"P3($&n;2Cx1QN9--L9,SA+T<+d__`:4,'

'A3GHFPY^bmj\^]\]??:)[TM3^O1%Q4)%''oA:D0:0OE.8ME-TE,XB,+`da;5['

'643IGQZ_cnk]_^]^@@;5\UN4_P2&R6*&(3B;E1<1PN99NL8WF.^C/,a+bY6,'

'7:F3HR[`dol^`_^_AA<6]VO5`Q3''S>+'');CBF:=:QOEEOO9_G8aH6/d,cZ[Y'

'8;G4IS\aep4_a`_-BD=7''XP6aR4(T?,(5@DCHCC;RPFLPPD`H9bJ70+0d\\Z'

'9BH>JT^bf45`ba`.CE@8(YQ7#S5)UD-)?AEDIDDD/QKMVQJ+S?cSDF,1e]a,'

':C3?K4_cg5[acbaADFA92ZR8$T6*VE.*@JFEJEEE0.NNWTK,U@+TEG0?+_bX'

';2D@L9`dh6\bdcbBEGD:3[S=)U7+cK/+CKGFLIKI9/OWZUL-VA,WIHB@,`cY'];

i = double(c(:)-32);

j = cumsum(diff([0; i])<=0) + 1;

S = sparse(i,j,1)';

spy(S)

Happy Easter / Passover everybody!

If you trust the comment at MATLAB answers: http://www.mathworks.com/matlabcentral/answers/2001-what-matlab-easter-eggs-do-you-know#answer_3077 it is Sean de Wolski’s dog. Sean is a relatively new employee at TMW and a frequent contributor to Answers. I think the dog is on his current avatar: http://www.mathworks.com/matlabcentral/answers/contributors/3208495-sean-de-wolski

Close, but it’s not Sean’s dog. The dog belongs to the lead developer of the sparse matrix functions in MATLAB.

I too was disappointed last year when I realized the spy was gone. Perhaps it is still reachable in some undocumented way?

@Naor – I’ve added an addendum showing how you can regenerate the old spy image

Hi Yair,

the spy snippet has a vertcat error in c as a poster mentioned on SO. I answered with the error free snippet here.

@Oleg – thanks. This was due to a bug in the WordPress code that renders < characters – It's now fixed. I had to revert to a sub-optimal non-syntax-highlighted rendering of the code, but at least it's now correct.