### Related

##### expintegral_si

expintegral_si(1);

Calculate

##### expintegral_si

expintegral_si(%pi);

Calculate

##### expintegral_si

? expintegral_si ;

Calculate

##### expintegral_si

expintegral_si (0.5);

Calculate

##### expintegral_si

expintegral_si (0.5);

Calculate

##### expintegral_si

expintegral_si(0.2);

Calculate

##### expintegral_si

expintegral_si(%pi);

Calculate

##### expintegral_si

expintegral_si (0.2) ;

Calculate

##### expintegral_si

expintegral_si(0.1);

Calculate

##### expintegral_si

? expintegral_si;

Calculate

### expintegral_si

Run Example
```(%i1)expintegral_si(0.99);
(%o1)                          0.93765334201444
(%i2) ```
Run Example
```assume (p >
0, a >
0);
(%o1)                           [p > 0, a > 0]
(%i2)  specint (t^(1/2) * exp(-a*t/4) * exp(-p*t), t);
sqrt(%pi)
(%o2)                            ------------
a 3/2
2 (p + -)
4
(%i3)  specint (t^(1/2) * bessel_j(1, 2 * a^(1/2) * t^(1/2))                        * exp(-p*t), t);
- a/p
sqrt(a) %e
(%o3)                           ---------------
2
p
(%i4)  assume(s>
0,a>
0,s-a>
0);
(%o4)                      [s > 0, redundant, s > a]
(%i5)  ratsimp(specint(%e^(a*t)*(log(a)+expintegral_e1(a*t))*%e^(-s*t),t));
log(s)
(%o5)                               ------
s - a
(%i6)  logarc:true;
(%o6)                                true
(%i7)  gamma_expand:true;
(%o7)                                true
log(s)
(%o8)                               ------
2
s  + 1
(%i9)  ratsimp(specint((2*t*log(a)+2/a*sin(a*t)                                -2*t*expintegral_ci(a*t))*%e^(-s*t),t));
2    2
log(s  + a )
(%o9)                            ------------
2
s
(%i10)  assume(s>
0);
(%o10)                            [redundant]
(%i11)  specint(1/sqrt(%pi*t)*unit_step(t-k)*%e^(-s*t),t);
erfc(sqrt(k) sqrt(s))
(%o11)                       ---------------------
sqrt(s)
(%i12)  gamma_expand:true;
(%o12)                               true
(%i13)  specint(1/sqrt(%pi*t)*unit_step(t-k)*%e^(-s*t),t);
erfc(sqrt(k) sqrt(s))
(%o13)                       ---------------------
sqrt(s)
(%i14)  expintrep:expintegral_e1;
(%o14)                          expintegral_e1
(%i15)  ratsimp(specint(1/(t+a)^2*%e^(-s*t),t));
a s
a s %e    expintegral_e1(a s) - 1
(%o15)                - ---------------------------------
a
(%i16) ```
Run Example
```expintegral_si(0.999);
(%o1)                           0.9452414488379
(%i2) ```

### Related Help

Help for Expintegral_si