3.5.1.1.21 IntegralIntegral-func
Description
Minimum Origin Version Required: 8.6 SR0
This function performs one dimension integration, and returns the integral value of:
And the function is called as the below form:
integral(integrandName, LowerLimit, UpperLimit [, arg1, arg2, ...])
Where integrandName here is the function name of the integrand , LowerLimit and UpperLimit can be used "-inf" and "+inf" as negative infinity and positive infinity respectively.
Notes: If there are discontinuous points or a sharp peak in the integral interval for the integral function, that may introduce dis-converge problem, in such situation we suggest user divide the integral interval into several parts to add refined sub-intervals around these points.
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Syntax
double Integral(integrandName, LowerLimit, UpperLimit [, arg1, arg2, ...])
Parameters
integrandName
- The name of the defined function to be integrated.
LowerLimit
- The lower limit of integral, "-inf" can be used as negative infinity.
UpperLimit
- The upper limit of integral, "+inf" can be used as positive infinity.
arg1, arg2, ...
- The arguments defined in the integrand.
Return
Return the integral value of specified integrand.
Example
// define quadratic equation as integrand
function double QuadraticEq(double x, double a, double b, double c) {
return a+b*x+c*x^2;
}
// integrate quadratic equation
Integral(QuadraticEq, 1, 4, 1, 2, 3) = ; // should return 81
Integral(QuadraticEq, -inf, +inf, 1, 2, 3) = ; // should return --, missing value
Algorithm
If LowerLimit is "-inf" or UpperLimit is "+inf", see: nag_1d_quad_inf_1 (d01smc)
Otherwise, see: nag_1d_quad_gen_1 (d01sjc).
See Also
Exp_integral, Elliptic_integral_rc, Elliptic_integral_rd, Elliptic_integral_rf, Elliptic_integral_rj, Cos_integral, Integrate
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