'Program WEALTH.BAS (c) 2012 by J. C. Sprott 'Calculates the distribution of wealth in a society subject to certain assumptions 'Use PowerBasic Console Compiler #DEBUG ERROR ON DEFEXT a-z FUNCTION PBMAIN() w&=500 'width of graph h&=500 'height of graph p&=1e6 'population size z&=1e5 'initial wealth y&=20 'number of years r&=20 'range of rates (percent) m&=1e6 'maximum wealth d&=2 'decades to plot CONSOLE SET LOC w&+6,0 CLS GRAPHIC WINDOW EXE.NAME\$, 0, 0, w&, h& TO hWin??? GRAPHIC ATTACH hWin???, 0 ', REDRAW GRAPHIC COLOR %BLACK, %WHITE GRAPHIC CLEAR GRAPHIC BOX(0,0)-(w&,h&) CONSOLE SET FOCUS RANDOMIZE TIMER DIM wealth(p&),rate(p&),wbin(w&) FOR i&=1 TO p& wealth(i&)=z& NEXT i& FOR i&=1 TO p& 'rate(i&)=0.01##*r&*(RND-0.5##) 'uniform random rate(i&)=0.005##*r&*gauss 'Gaussian random FOR year&=1 TO y& 'rate=0.01##*r&*(rnd-0.5##) 'different rate every year rate=rate(i&) 'same rate every year 'rate=0.5##*rate(i&)+0.5##*0.01##*r&*(RND-0.5##) 'mixed rate 'rate=0.5##*rate(i&)+0.5##*0.005##*r&*gauss 'mixed rate Gaussian wealth(i&)=(1##+rate)*wealth(i&) NEXT year& wb&=INT(w&+w&*LOG10(wealth(i&)/m&)/d&) IF wb&>0 AND wb&<=w& THEN wbin(wb&)=wbin(wb&)+10^(-d&*wb&/w&) wbm&=MAX(wbm&,wbin(wb&)) END IF NEXT i& FOR x&=1 TO w& IF wbin(x&)=0 THEN y&=h& ELSE y&=-h&*LOG10(wbin(x&)/wbm&)/d& END IF IF x&=1 THEN GRAPHIC SET PIXEL(x&,y&) ELSE GRAPHIC LINE-(x&,y&) PRINT x&,y& NEXT w& GRAPHIC SAVE"wealth4.bmp" WAITKEY\$ END FUNCTION FUNCTION gauss 'Returns a normally (Gaussian) distributed random deviate 'with mean of zero and standard deviation of 1.0 DO V1 = 2## * RND - 1## V2 = 2## * RND - 1## R = V1 * V1 + V2 * V2 LOOP WHILE R >= 1## OR R = 0## GAUSS = V2 * SQR(-2## * LOG(R) / R) END FUNCTION