diff --git a/README.md b/README.md
index d47016a2a..586d2185f 100644
--- a/README.md
+++ b/README.md
@@ -257,8 +257,8 @@ repositories {
 }
 
 dependencies {
-    api("kscience.kmath:kmath-core:0.2.0-dev-6")
-    // api("kscience.kmath:kmath-core-jvm:0.2.0-dev-6") for jvm-specific version
+    api("kscience.kmath:kmath-core:0.2.0-dev-7")
+    // api("kscience.kmath:kmath-core-jvm:0.2.0-dev-7") for jvm-specific version
 }
 ```
 
diff --git a/examples/src/benchmarks/kotlin/kscience/kmath/benchmarks/BufferBenchmark.kt b/examples/src/benchmarks/kotlin/kscience/kmath/benchmarks/BufferBenchmark.kt
index 42a03bc53..e14b393e2 100644
--- a/examples/src/benchmarks/kotlin/kscience/kmath/benchmarks/BufferBenchmark.kt
+++ b/examples/src/benchmarks/kotlin/kscience/kmath/benchmarks/BufferBenchmark.kt
@@ -1,7 +1,7 @@
 package kscience.kmath.benchmarks
 
-import kscience.kmath.operations.Complex
-import kscience.kmath.operations.complex
+import kscience.kmath.complex.Complex
+import kscience.kmath.complex.complex
 import kscience.kmath.structures.MutableBuffer
 import kscience.kmath.structures.RealBuffer
 import org.openjdk.jmh.annotations.Benchmark
diff --git a/kmath-ast/README.md b/kmath-ast/README.md
index 8499f7171..c54c4afb1 100644
--- a/kmath-ast/README.md
+++ b/kmath-ast/README.md
@@ -12,7 +12,7 @@ This subproject implements the following features:
 
 > #### Artifact:
 >
-> This module artifact: `kscience.kmath:kmath-ast:0.2.0-dev-6`.
+> This module artifact: `kscience.kmath:kmath-ast:0.2.0-dev-7`.
 >
 > Bintray release version:        [ ![Download](https://api.bintray.com/packages/mipt-npm/kscience/kmath-ast/images/download.svg) ](https://bintray.com/mipt-npm/kscience/kmath-ast/_latestVersion)
 >
@@ -30,7 +30,7 @@ This subproject implements the following features:
 > }
 > 
 > dependencies {
->     implementation 'kscience.kmath:kmath-ast:0.2.0-dev-6'
+>     implementation 'kscience.kmath:kmath-ast:0.2.0-dev-7'
 > }
 > ```
 > **Gradle Kotlin DSL:**
@@ -44,7 +44,7 @@ This subproject implements the following features:
 > }
 > 
 > dependencies {
->     implementation("kscience.kmath:kmath-ast:0.2.0-dev-6")
+>     implementation("kscience.kmath:kmath-ast:0.2.0-dev-7")
 > }
 > ```
 
@@ -75,7 +75,7 @@ import kscience.kmath.expressions.Symbol;
 public final class AsmCompiledExpression_45045_0 implements Expression<Double> {
     private final Object[] constants;
 
-    public final Double invoke(Map<Symbol, Double> arguments) {
+    public final Double invoke(Map<Symbol, ? extends Double> arguments) {
         return (Double)((Function2)this.constants[0]).invoke((Double)MapIntrinsics.getOrFail(arguments, "x"), 2);
     }
 
diff --git a/kmath-ast/docs/README-TEMPLATE.md b/kmath-ast/docs/README-TEMPLATE.md
index 3227a2ad3..ebaa6246a 100644
--- a/kmath-ast/docs/README-TEMPLATE.md
+++ b/kmath-ast/docs/README-TEMPLATE.md
@@ -33,7 +33,7 @@ import kscience.kmath.expressions.Symbol;
 public final class AsmCompiledExpression_45045_0 implements Expression<Double> {
     private final Object[] constants;
 
-    public final Double invoke(Map<Symbol, Double> arguments) {
+    public final Double invoke(Map<Symbol, ? extends Double> arguments) {
         return (Double)((Function2)this.constants[0]).invoke((Double)MapIntrinsics.getOrFail(arguments, "x"), 2);
     }
 
diff --git a/kmath-ast/src/jvmMain/kotlin/kscience/kmath/asm/internal/AsmBuilder.kt b/kmath-ast/src/jvmMain/kotlin/kscience/kmath/asm/internal/AsmBuilder.kt
index 93d8d1143..cd1236b70 100644
--- a/kmath-ast/src/jvmMain/kotlin/kscience/kmath/asm/internal/AsmBuilder.kt
+++ b/kmath-ast/src/jvmMain/kotlin/kscience/kmath/asm/internal/AsmBuilder.kt
@@ -83,7 +83,7 @@ internal class AsmBuilder<T>(
                 ACC_PUBLIC or ACC_FINAL,
                 "invoke",
                 getMethodDescriptor(tType, MAP_TYPE),
-                "(L${MAP_TYPE.internalName}<${SYMBOL_TYPE.descriptor}${if (Modifier.isFinal(classOfT.modifiers)) "" else "+"}${tType.descriptor}>;)${tType.descriptor}",
+                "(L${MAP_TYPE.internalName}<${SYMBOL_TYPE.descriptor}+${tType.descriptor}>;)${tType.descriptor}",
                 null,
             ).instructionAdapter {
                 invokeMethodVisitor = this
diff --git a/kmath-complex/README.md b/kmath-complex/README.md
index eecb6b205..8e5320225 100644
--- a/kmath-complex/README.md
+++ b/kmath-complex/README.md
@@ -8,7 +8,7 @@ Complex and hypercomplex number systems in KMath:
 
 > #### Artifact:
 >
-> This module artifact: `kscience.kmath:kmath-complex:0.2.0-dev-6`.
+> This module artifact: `kscience.kmath:kmath-complex:0.2.0-dev-7`.
 >
 > Bintray release version:        [ ![Download](https://api.bintray.com/packages/mipt-npm/kscience/kmath-complex/images/download.svg) ](https://bintray.com/mipt-npm/kscience/kmath-complex/_latestVersion)
 >
@@ -26,7 +26,7 @@ Complex and hypercomplex number systems in KMath:
 > }
 > 
 > dependencies {
->     implementation 'kscience.kmath:kmath-complex:0.2.0-dev-6'
+>     implementation 'kscience.kmath:kmath-complex:0.2.0-dev-7'
 > }
 > ```
 > **Gradle Kotlin DSL:**
@@ -40,6 +40,6 @@ Complex and hypercomplex number systems in KMath:
 > }
 > 
 > dependencies {
->     implementation("kscience.kmath:kmath-complex:0.2.0-dev-6")
+>     implementation("kscience.kmath:kmath-complex:0.2.0-dev-7")
 > }
 > ```
diff --git a/kmath-core/README.md b/kmath-core/README.md
index 504171fe2..a38b3acaa 100644
--- a/kmath-core/README.md
+++ b/kmath-core/README.md
@@ -15,7 +15,7 @@ performance calculations to code generation.
 
 > #### Artifact:
 >
-> This module artifact: `kscience.kmath:kmath-core:0.2.0-dev-6`.
+> This module artifact: `kscience.kmath:kmath-core:0.2.0-dev-7`.
 >
 > Bintray release version:        [ ![Download](https://api.bintray.com/packages/mipt-npm/kscience/kmath-core/images/download.svg) ](https://bintray.com/mipt-npm/kscience/kmath-core/_latestVersion)
 >
@@ -33,7 +33,7 @@ performance calculations to code generation.
 > }
 > 
 > dependencies {
->     implementation 'kscience.kmath:kmath-core:0.2.0-dev-6'
+>     implementation 'kscience.kmath:kmath-core:0.2.0-dev-7'
 > }
 > ```
 > **Gradle Kotlin DSL:**
@@ -47,6 +47,6 @@ performance calculations to code generation.
 > }
 > 
 > dependencies {
->     implementation("kscience.kmath:kmath-core:0.2.0-dev-6")
+>     implementation("kscience.kmath:kmath-core:0.2.0-dev-7")
 > }
 > ```
diff --git a/kmath-core/src/commonMain/kotlin/kscience/kmath/linear/MatrixContext.kt b/kmath-core/src/commonMain/kotlin/kscience/kmath/linear/MatrixContext.kt
index 8766f2e5f..234435b29 100644
--- a/kmath-core/src/commonMain/kotlin/kscience/kmath/linear/MatrixContext.kt
+++ b/kmath-core/src/commonMain/kotlin/kscience/kmath/linear/MatrixContext.kt
@@ -9,7 +9,10 @@ import kscience.kmath.structures.BufferFactory
 import kscience.kmath.structures.asSequence
 
 /**
- * Basic operations on matrices. Operates on [Matrix]
+ * Basic operations on matrices. Operates on [Matrix].
+ *
+ * @param T the type of items in the matrices.
+ * @param M the type of operated matrices.
  */
 public interface MatrixContext<T : Any, out M : Matrix<T>> : SpaceOperations<Matrix<T>> {
     /**
@@ -83,9 +86,16 @@ public interface MatrixContext<T : Any, out M : Matrix<T>> : SpaceOperations<Mat
     }
 }
 
+/**
+ * Partial implementation of [MatrixContext] for matrices of [Ring].
+ *
+ * @param T the type of items in the matrices.
+ * @param R the type of ring of matrix elements.
+ * @param M the type of operated matrices.
+ */
 public interface GenericMatrixContext<T : Any, R : Ring<T>, out M : Matrix<T>> : MatrixContext<T, M> {
     /**
-     * The ring context for matrix elements
+     * The ring over matrix elements.
      */
     public val elementContext: R
 
diff --git a/kmath-core/src/commonMain/kotlin/kscience/kmath/linear/VirtualMatrix.kt b/kmath-core/src/commonMain/kotlin/kscience/kmath/linear/VirtualMatrix.kt
index df4e4de09..c96e55be6 100644
--- a/kmath-core/src/commonMain/kotlin/kscience/kmath/linear/VirtualMatrix.kt
+++ b/kmath-core/src/commonMain/kotlin/kscience/kmath/linear/VirtualMatrix.kt
@@ -1,5 +1,10 @@
 package kscience.kmath.linear
 
+/**
+ * The matrix where each element is evaluated each time when is being accessed.
+ *
+ * @property generator the function that provides elements.
+ */
 public class VirtualMatrix<T : Any>(
     override val rowNum: Int,
     override val colNum: Int,
diff --git a/kmath-core/src/commonMain/kotlin/kscience/kmath/nd/Structure2D.kt b/kmath-core/src/commonMain/kotlin/kscience/kmath/nd/Structure2D.kt
index 32e0704fc..e2694309a 100644
--- a/kmath-core/src/commonMain/kotlin/kscience/kmath/nd/Structure2D.kt
+++ b/kmath-core/src/commonMain/kotlin/kscience/kmath/nd/Structure2D.kt
@@ -86,3 +86,10 @@ public fun <T> NDStructure<T>.as2D(): Structure2D<T> = if (shape.size == 2)
     Structure2DWrapper(this)
 else
     error("Can't create 2d-structure from ${shape.size}d-structure")
+
+/**
+ * Alias for [Structure2D] with more familiar name.
+ *
+ * @param T the type of items in the matrix.
+ */
+public typealias Matrix<T> = Structure2D<T>
diff --git a/kmath-core/src/commonMain/kotlin/kscience/kmath/operations/Algebra.kt b/kmath-core/src/commonMain/kotlin/kscience/kmath/operations/Algebra.kt
index f3a87d644..14006ea10 100644
--- a/kmath-core/src/commonMain/kotlin/kscience/kmath/operations/Algebra.kt
+++ b/kmath-core/src/commonMain/kotlin/kscience/kmath/operations/Algebra.kt
@@ -95,8 +95,8 @@ public interface Algebra<T> {
 public inline operator fun <A : Algebra<*>, R> A.invoke(block: A.() -> R): R = run(block)
 
 /**
- * Represents "semispace", i.e. algebraic structure with associative binary operation called "addition" as well as
- * multiplication by scalars.
+ * Represents linear space without neutral element, i.e. algebraic structure with associative, binary operation [add]
+ * and scalar multiplication [multiply].
  *
  * @param T the type of element of this semispace.
  */
@@ -208,10 +208,10 @@ public interface SpaceOperations<T> : Algebra<T> {
 }
 
 /**
- * Represents linear space, i.e. algebraic structure with associative binary operation called "addition" and its neutral
- * element as well as multiplication by scalars.
+ * Represents linear space with neutral element, i.e. algebraic structure with associative, binary operation [add] and
+ * scalar multiplication [multiply].
  *
- * @param T the type of element of this group.
+ * @param T the type of element of this semispace.
  */
 public interface Space<T> : SpaceOperations<T> {
     /**
@@ -221,8 +221,8 @@ public interface Space<T> : SpaceOperations<T> {
 }
 
 /**
- * Represents semiring, i.e. algebraic structure with two associative binary operations called "addition" and
- * "multiplication".
+ * Represents rng, i.e. algebraic structure with associative, binary, commutative operation [add] and associative,
+ * operation [multiply] distributive over [add].
  *
  * @param T the type of element of this semiring.
  */
@@ -270,8 +270,8 @@ public interface Ring<T> : Space<T>, RingOperations<T> {
 }
 
 /**
- * Represents semifield, i.e. algebraic structure with three operations: associative "addition" and "multiplication",
- * and "division".
+ * Represents field without identity elements, i.e. algebraic structure with associative, binary, commutative operations
+ * [add] and [multiply]; binary operation [divide] as multiplication of left operand by reciprocal of right one.
  *
  * @param T the type of element of this semifield.
  */
diff --git a/kmath-for-real/README.md b/kmath-for-real/README.md
index 9b191121d..c291be3a1 100644
--- a/kmath-for-real/README.md
+++ b/kmath-for-real/README.md
@@ -7,7 +7,7 @@
 
 > #### Artifact:
 >
-> This module artifact: `kscience.kmath:kmath-for-real:0.2.0-dev-6`.
+> This module artifact: `kscience.kmath:kmath-for-real:0.2.0-dev-7`.
 >
 > Bintray release version:        [ ![Download](https://api.bintray.com/packages/mipt-npm/kscience/kmath-for-real/images/download.svg) ](https://bintray.com/mipt-npm/kscience/kmath-for-real/_latestVersion)
 >
@@ -25,7 +25,7 @@
 > }
 > 
 > dependencies {
->     implementation 'kscience.kmath:kmath-for-real:0.2.0-dev-6'
+>     implementation 'kscience.kmath:kmath-for-real:0.2.0-dev-7'
 > }
 > ```
 > **Gradle Kotlin DSL:**
@@ -39,6 +39,6 @@
 > }
 > 
 > dependencies {
->     implementation("kscience.kmath:kmath-for-real:0.2.0-dev-6")
+>     implementation("kscience.kmath:kmath-for-real:0.2.0-dev-7")
 > }
 > ```
diff --git a/kmath-functions/README.md b/kmath-functions/README.md
index 3e3d96fe9..f5462e09f 100644
--- a/kmath-functions/README.md
+++ b/kmath-functions/README.md
@@ -10,7 +10,7 @@ Functions and interpolations:
 
 > #### Artifact:
 >
-> This module artifact: `kscience.kmath:kmath-functions:0.2.0-dev-6`.
+> This module artifact: `kscience.kmath:kmath-functions:0.2.0-dev-7`.
 >
 > Bintray release version:        [ ![Download](https://api.bintray.com/packages/mipt-npm/kscience/kmath-functions/images/download.svg) ](https://bintray.com/mipt-npm/kscience/kmath-functions/_latestVersion)
 >
@@ -28,7 +28,7 @@ Functions and interpolations:
 > }
 > 
 > dependencies {
->     implementation 'kscience.kmath:kmath-functions:0.2.0-dev-6'
+>     implementation 'kscience.kmath:kmath-functions:0.2.0-dev-7'
 > }
 > ```
 > **Gradle Kotlin DSL:**
@@ -42,6 +42,6 @@ Functions and interpolations:
 > }
 > 
 > dependencies {
->     implementation("kscience.kmath:kmath-functions:0.2.0-dev-6")
+>     implementation("kscience.kmath:kmath-functions:0.2.0-dev-7")
 > }
 > ```
diff --git a/kmath-nd4j/README.md b/kmath-nd4j/README.md
index 5ef42bab3..9011ef3c5 100644
--- a/kmath-nd4j/README.md
+++ b/kmath-nd4j/README.md
@@ -9,7 +9,7 @@ This subproject implements the following features:
 
 > #### Artifact:
 >
-> This module artifact: `kscience.kmath:kmath-nd4j:0.2.0-dev-6`.
+> This module artifact: `kscience.kmath:kmath-nd4j:0.2.0-dev-7`.
 >
 > Bintray release version:        [ ![Download](https://api.bintray.com/packages/mipt-npm/kscience/kmath-nd4j/images/download.svg) ](https://bintray.com/mipt-npm/kscience/kmath-nd4j/_latestVersion)
 >
@@ -27,7 +27,7 @@ This subproject implements the following features:
 > }
 > 
 > dependencies {
->     implementation 'kscience.kmath:kmath-nd4j:0.2.0-dev-6'
+>     implementation 'kscience.kmath:kmath-nd4j:0.2.0-dev-7'
 > }
 > ```
 > **Gradle Kotlin DSL:**
@@ -41,7 +41,7 @@ This subproject implements the following features:
 > }
 > 
 > dependencies {
->     implementation("kscience.kmath:kmath-nd4j:0.2.0-dev-6")
+>     implementation("kscience.kmath:kmath-nd4j:0.2.0-dev-7")
 > }
 > ```