why isnt the variable pg$1$ recognized in the lines below function $[$T$,$ P$]=$ stdatm$\_$MuetzelDonovan$($h$)$

$\%$ Define Constants

g$=9\mathrm{.}8$;

R$=287$;

t$=288\mathrm{.}16$;

p$=101\mathrm{.}325$;

d$=1\mathrm{.}225$;

e$=$exp$(1)$;

$\%$Calculate temp, pressure, and density of a given height

$\%$ calculate temprature first line, pressure second, density $3$rd line

if h$<11000\%$g$1$

T $=288\mathrm{.}16-(\mathrm{.}0065*$h$)$;

P$=((($T$/$t$)^(-$g$/(-\mathrm{.}0065*$R$))))*$p;

pg$1=((216\mathrm{.}66/$t$)^(-$g$/(-\mathrm{.}0065*$R$)))*$p;

elseif $(11000<$ h$)$ && $($h $<25000)\%$i$1$

T$=288\mathrm{.}16-(\mathrm{.}0065*11000)$;

P$=$e$^(-(($g$*($h$-11000))/($R$*$T$)))*($pg$1)$;

pi$1=$e$^(-(($g$*(25000-11000))/($R$*$T$)))*($pg$1)$;

elseif $(25000<$ h$)$ && $($h $<47000)\%$g$2$

T$=288\mathrm{.}16-(\mathrm{.}0065*11000)+(\mathrm{.}003*($h$-25000))$;

P$=(($T$/$t$)^($g$/(\mathrm{.}003*$R$))*$p$)+$pi$1$;

pg$2=((291\mathrm{.}6/$t$)^(-$g$/(\mathrm{.}003*$R$))*$p$)+$pi$1$;

elseif $(47000<$ h$)$ && $($h $<53000)\%$i$2$

T$=288\mathrm{.}16-(\mathrm{.}0065*11000)+(\mathrm{.}003*25000)$;

P$=$e$^(-(($g$*($h$-47000))/$R$*$p$))*$pg$2$;

pi$2=$e$^(-(($g$*(53000-47000))/$R$*$T$))*$pg$2$;

elseif $(53000<$ h$)$ && $($h $<79000)\%$g$3$

T$=288\mathrm{.}16-(\mathrm{.}0065*11000)+(\mathrm{.}003*25000)-(\mathrm{.}0045*($h$-53000))$;

P$=(($T$/$t$)^($g$/(\mathrm{.}003*$R$))*$p$)+$pi$2$;

pg$3=((179\mathrm{.}16/$t$)^(-$g$/(\mathrm{.}003*$R$))*$p$)+$pi$2$;

elseif $(79000<$ h$)$ && $($h $<90000)\%$i$3$

T$=288\mathrm{.}16-(\mathrm{.}0065*11000)+(\mathrm{.}003*25000)-(\mathrm{.}0045*53000)$;

P$=$e$^(-(($g$*($h$-79000))/$R$*$p$))*$pg$3$;

pi$3=$ e$^(-(($g$*(90000-79000))/$R$*$T$))*$pg$3$;

elseif $(90000<$ h$)$ && $($h $<100000)\%$g$4$

T$=288\mathrm{.}16-(\mathrm{.}0065*11000)+(\mathrm{.}003*25000)-(\mathrm{.}0045*(53000))+(\mathrm{.}004*($h$-90000))$;

P$=(($T$/$t$)^($g$/(\mathrm{.}003*$R$))*$p$)+$pi$3$;

pg$4=((53\mathrm{.}16/$t$)^(-$g$/(\mathrm{.}003*$R$))*$p$)+$pi$3$;

end