Gamma函数相关matlab代码

x=0:0.5:5
syms t
y=int(t.^(x-1)*exp(-t),0,inf)
y=double(y)
plot(x,y,'r-o','linewidth',1)

x=0:0.1:5
syms t
y=int(t.^(x-1)*exp(-t),0,inf)
y=log10(double(y))
plot(x,y,'r-o','linewidth',1)

a=1,b=0.5
syms c
d=int(c^(a-1)*exp(-c),0,inf)
t=0:0.1:20
g=b.^a*(t.^(a-1)).*exp(-b*t)/d
g=double(g)
plot(t,g,'r-.','linewidth',1)

t=0:0.1:20
syms c

a=1,b=0.5
d=int(c^(a-1)*exp(-c),0,inf)
g=b.^a*(t.^(a-1)).*exp(-b*t)/d
g=double(g)
plot(t,g,'r-.','linewidth',1)
hold on;
a=2,b=0.5
d=int(c^(a-1)*exp(-c),0,inf)
g=b.^a*(t.^(a-1)).*exp(-b*t)/d
g=double(g)
plot(t,g,'g-.','linewidth',1)
hold on
a=3,b=0.5
d=int(c^(a-1)*exp(-c),0,inf)
g=b.^a*(t.^(a-1)).*exp(-b*t)/d
g=double(g)
plot(t,g,'b-.','linewidth',1)
hold on
a=5,b=1
d=int(c^(a-1)*exp(-c),0,inf)
g=b.^a*(t.^(a-1)).*exp(-b*t)/d
g=double(g)
plot(t,g,'c-.','linewidth',1)
hold on
a=9,b=2
d=int(c^(a-1)*exp(-c),0,inf)
g=b.^a*(t.^(a-1)).*exp(-b*t)/d
g=double(g)
plot(t,g,'m-.','linewidth',1)
hold on;
legend('a=1,b=0.5','a=2,b=0.5','a=3,b=0.5','a=5,b=1','a=9,b=2');