Fix Symja build issues

build.gradle.kts

@@ -10,7 +10,9 @@ allprojects {
         maven("http://logicrunch.research.it.uu.se/maven") {
             isAllowInsecureProtocol = true
         }
-        maven("https://oss.sonatype.org/content/repositories/snapshots")
+        maven("https://oss.sonatype.org/content/repositories/snapshots") {
+
+        }
         mavenCentral()
     }
 
@@ -31,6 +33,7 @@ subprojects {
                 externalDocumentationLink("http://ejml.org/javadoc/")
                 externalDocumentationLink("https://commons.apache.org/proper/commons-math/javadocs/api-3.6.1/")
                 externalDocumentationLink("https://deeplearning4j.org/api/latest/")
+                externalDocumentationLink("https://axelclk.bitbucket.io/symja/javadoc/")
                 externalDocumentationLink("https://kotlin.github.io/kotlinx.coroutines/kotlinx-coroutines-core/")
             }
         }

kmath-symja/build.gradle.kts

@@ -11,7 +11,14 @@ plugins {
 description = "Symja integration module"
 
 dependencies {
-    api("org.matheclipse:matheclipse-core:2.0.0-SNAPSHOT")
+    api("org.matheclipse:matheclipse-core:2.0.0-SNAPSHOT") {
+        // Incorrect transitive dependency org.apfloat:apfloat:1.10.0-SNAPSHOT
+        exclude("org.apfloat", "apfloat")
+    }
+
+    // Replace for org.apfloat:apfloat:1.10.0-SNAPSHOT
+    api("org.apfloat:apfloat:1.10.0")
+
     api(project(":kmath-core"))
     testImplementation("org.slf4j:slf4j-simple:1.7.30")
 }

kmath-symja/src/main/kotlin/space/kscience/kmath/symja/SymjaExpression.kt

@@ -7,17 +7,28 @@ package space.kscience.kmath.symja
 
 import org.matheclipse.core.eval.ExprEvaluator
 import org.matheclipse.core.expression.F
-import space.kscience.kmath.expressions.DifferentiableExpression
+import space.kscience.kmath.expressions.SpecialDifferentiableExpression
 import space.kscience.kmath.expressions.MST
 import space.kscience.kmath.expressions.Symbol
 import space.kscience.kmath.expressions.interpret
 import space.kscience.kmath.operations.NumericAlgebra
 
+/**
+ * Represents [MST] based [DifferentiableExpression] relying on [Symja](https://github.com/axkr/symja_android_library).
+ *
+ * The principle of this API is converting the [mst] to an [org.matheclipse.core.interfaces.IExpr], differentiating it
+ * with Symja's [F.D], then converting [org.matheclipse.core.interfaces.IExpr] back to [MST].
+ *
+ * @param T The type of number.
+ * @param A The [NumericAlgebra] of [T].
+ * @property algebra The [A] instance.
+ * @property mst The [MST] node.
+ */
 public class SymjaExpression<T : Number, A : NumericAlgebra<T>>(
     public val algebra: A,
     public val mst: MST,
     public val evaluator: ExprEvaluator = DEFAULT_EVALUATOR,
-) : DifferentiableExpression<T, SymjaExpression<T, A>> {
+) : SpecialDifferentiableExpression<T, SymjaExpression<T, A>> {
     public override fun invoke(arguments: Map<Symbol, T>): T = mst.interpret(algebra, arguments)
 
     public override fun derivativeOrNull(symbols: List<Symbol>): SymjaExpression<T, A> = SymjaExpression(