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TestLCLoop.java
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134 lines (118 loc) · 3.56 KB
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package lambdacloud.test;
import static symjava.math.SymMath.cos;
import lambdacloud.core.CloudFunc;
import lambdacloud.core.CloudSD;
import lambdacloud.core.lang.LCBuilder;
import lambdacloud.core.lang.LCInt;
import lambdacloud.core.lang.LCLoop;
import lambdacloud.core.lang.LCReturn;
import lambdacloud.core.lang.LCStatements;
import lambdacloud.core.lang.LCVar;
import symjava.math.SymMath;
import symjava.relational.Lt;
import symjava.symbolic.Expr;
public class TestLCLoop {
/**
* Test a simple loop
*/
public static void testLoop1() {
LCInt i = new LCInt("i");
LCVar x = LCVar.getDouble("x");
LCStatements lcs1 = new LCStatements();
//for(int i=0; i<100; i++);
LCLoop loop = new LCLoop(
i.assign(0), //i = 0
Lt.apply(i, 100), //i < 100
i.assign(i + 1) //i = i+1
);
lcs1.append(loop);
lcs1.append(new LCReturn(x));
System.out.println(lcs1);
System.out.println(CompileUtils.compile(lcs1).apply());
//int i=0;
//while(i<100) {
// i++;
//}
LCStatements lcs2 = new LCStatements();
LCLoop loop2 = new LCLoop(
i.assign(0), //i = 0
Lt.apply(i, 100) //i < 100
);
loop2.appendBody(i.assign(i + 1)); // i=i+1
lcs2.append(loop2);
lcs2.append(new LCReturn(x));
System.out.println(lcs2);
System.out.println(CompileUtils.compile(lcs2).apply());
}
/**
* Use Newton's method to solve x = cos(x) with initial value x0=1.0
* (http://www.sosmath.com/calculus/diff/der07/der07.html)
*
* The following function is generated for the cloud task server.
* double apply(double x) {
* for(int i=0; i<100; i++) {
* double dx = -f(x)/df(x); //Symbolic expression
* if(abs(dx) < 1e-5) break;
* x = x + dx;
* }
* return x;
* }
*
* Results:
* x_1=1.
* x_2=0.750363867840
* ...
* x_8=0.739085133215
*/
public static void testLoop2() {
LCBuilder lcb = new LCBuilder("server");
// Compute the derivative of f(x) locally
LCVar x = LCVar.getDouble("x");
Expr f = x - cos(x);
Expr df = f.diff(x);
System.out.println("f(x)="+f+" f.diff(x)="+df);
int maxIter = 100;
LCInt i = new LCInt("i"); //int i = 0;
LCVar dx = LCVar.getDouble("dx"); //double dx = 0;
lcb.For(i.assign(0), Lt.apply(i, maxIter), i.inc()) // for(int i=0; i<100; i++) {
.appendBody( dx.assign(-f/df) ) // dx = -f(x)/df(x);
.breakIf(Lt.apply(SymMath.abs(dx), 1e-5)) // if(dx < 1e-5) break;
.appendBody(x.assign(x + dx)) // x = x + dx;
; // }
lcb.Return(x); // return x;
System.out.println(lcb);
// Build function: double apply(double x)
CloudFunc func = lcb.build(x);
// Define the cloud shared variables to store the initial value and solution
CloudSD x0 = new CloudSD("x0");
x0.init(new double[] { 1.0 });
x0.push();
CloudSD ans = new CloudSD("ans").resize(1);
func.apply(ans, x0); // Run the function on the cloud task server
// Get the result. (=0.7390851)
ans.fetch();
System.out.println("Solution: "+ans.getData(0));
System.out.println("Verify: "+applyTest(1.0));
}
/**
* Verify the solution locally
* @param x
* @return
*/
public static double applyTest(double x) {
int i = 0;
for(; i < 100; i++) {
double dx = -(-Math.cos(x) + x)/(1 + Math.sin(x));
if( Math.abs(dx) < 1.0E-5 ) {
break;
}
x = dx + x;
}
System.out.println("Max iter="+i);
return x;
}
public static void main(String[] args) {
testLoop1();
testLoop2();
}
}